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{{Short description|Council of Christian bishops in Nicaea, 325}}
{{Use dmy dates|date=May 2018}}
{{Infobox ecumenical council
| council_name = First Council of Nicaea
| council_date = May to August 325
| image = Nikea-arius.png 
| caption = The Council of Nicaea, with Arius depicted as defeated by the council, lying under the feet of Emperor Constantine. The [[Hagia Sophia]] is in the background of the icon (despite the fact that its construction had not yet begun at this point). 
| accepted_by = {{plainlist|
* [[Catholic Church]]
* [[Eastern Orthodox Church]]
* [[Oriental Orthodox Church]]
* [[Church of the East]]
* [[Lutheran Church]]es
* [[Anglican Church]]es
* [[Reformed Church]]es<ref>{{cite book |last1=Olson |first1=Roger E. |title=The Story of Christian Theology: Twenty Centuries of Tradition Reform |date=1 April 1999 |publisher=InterVarsity Press |isbn=978-0-8308-1505-0 |page=158 |language=English}}</ref>}}
| next = [[First Council of Constantinople]]
| convoked_by = Emperor [[Constantine the Great|Constantine I]]
| presided_by = [[Hosius of Corduba]] 
| attendance = {{ubl|318 (traditional number)|250–318 (estimates) – only five from Western Church}}
| topics = [[Arianism]], the nature of Christ, celebration of Passover, [[ordination]] of eunuchs, prohibition of kneeling on Sundays and from Easter to Pentecost, validity of [[baptism]] by heretics, lapsed Christians, sundry other matters<ref name="harvnb|SEC|pp=112–114">{{harvnb|SEC|pp=112–114}}</ref>
| documents = [[Nicene Creed#Original Nicene Creed of 325|Original Nicene Creed]],<ref name="harvnb|SEC|p=39">{{harvnb|SEC|p=39}}</ref> 20 [[Canon (canon law)|canon]]s,<ref name="harvnb|SEC|pp=44–94">{{harvnb|SEC|pp=44–94}}</ref> and a synodal epistle<ref name="harvnb|SEC|pp=112–114" />
}}
{{Oriental Orthodox sidebar|expanded=history}}
{{Eastern Orthodox sidebar|expanded=councils}}
{{Ecumenical councils of the Catholic Church}}

The '''First Council of Nicaea''' ({{IPAc-en|n|aɪ|ˈ|s|i:|ə}} {{respell|ny|SEE|ə}}; {{langx|grc|Σύνοδος τῆς Νίκαιας|Sýnodos tês Níkaias}}) was a council of Christian bishops convened in the [[Bithynia]]n city of [[Nicaea]] (now [[İznik]], [[Turkey]]) by the [[Roman emperor|Roman Emperor]] [[Constantine the Great|Constantine I]]. The Council of Nicaea met from May until the end of July 325.{{sfn|Hanson|1988|p=152}}

This [[ecumenical council]] was the first of many efforts to attain [[consensus decision-making|consensus]] in the church through an [[legislature|assembly]] representing all [[Christendom]]. [[Hosius of Corduba]] may have presided over its deliberations.<ref name="Carroll 1987 11">{{harvnb|Carroll|1987|p=11}}</ref>{{sfn|Vallaud|1995|pp=234–235, 678}} [[List of attendees and signatories of the First Council of Nicaea|Attended by at least 200 bishops]], its main accomplishments were the settlement of the [[Christology|Christological]] issue of the divine nature of [[God the Son]] and his relationship to [[God the Father#Christianity|God the Father]],<ref name="harvnb|SEC|p=39" /> the construction of the first part of the [[Nicene Creed]], the mandating of uniform observance of the [[date of Easter]],<ref name="ReferenceB">{{harvnb|On the Keeping of Easter}}</ref> and the promulgation of early [[canon law]].<ref name="harvnb|SEC|pp=44–94" /><ref>{{harvnb|Leclercq|1911b}}</ref>

== Background ==
{{further|Christianity in the ante-Nicene period}}

=== Alexandrian controversies ===
{{main|Arian controversy|Melitians}}
The major impetus for the calling of the Council of Nicaea arose in a theological dispute among the Christian clergy of [[Alexandria]] concerning the nature of [[Jesus]], his origin, and relation to [[God the Father]].{{sfn|Lyman|2021|pp=43–44, 46}} Scholars propose dates between 318 and 322 for the beginning of the dispute.{{sfn|Lyman|2021|p=46}} The precise origins of the controversy are unclear, but the principal actors were [[Pope Alexander I of Alexandria|Archbishop Alexander of Alexandria]] and the presbyter [[Arius]].{{sfn|Hanson|1988|pp=130–132}} Arius' teachings are known partially from a few pieces of his writings which survive, but principally from his opponents, primarily Alexander and [[Athanasius of Alexandria]].{{sfn|Hanson|1988|pp=5–6}}{{sfn|Lyman|2021|pp=46, 57–60}} Arius criticized Alexander's teachings on [[Christology]]; Alexander taught that Jesus as [[God the Son]] was eternally generated from the Father, while Arius and his followers asserted that the Father alone was eternal, and that the Son was created or begotten by the Father, and thus had a defined point of origin and was subordinate to the Father.{{sfn|Hanson|1988|pp=1, 6–7}}{{sfn|Lyman|2021|pp=47–50}} Arius accused Alexander of following [[Sabellianism|the teachings]] of [[Sabellius]], who taught that the Father, Son, and Holy Spirit were one person, rather than the view held throughout the east that they were distinct.{{sfn|Edwards|2006|p=554}} Alexander called a local council of bishops from Egypt and Libya, which sided with Alexander's view. Arius refused to subscribe to the council's decision, and he and several followers were excommunicated and exiled from Alexandria by Alexander. Arius then traveled to churches around the Roman east and wrote to bishops to gain support of his view. Among Arius' supporters were [[Eusebius of Nicomedia]] and [[Eusebius|Eusebius of Caesarea]], and they advocated for his view and his restoration to the church in Alexandria. Alexander also circulated letters defending his own position.{{sfn|Hanson|1988|pp=134–135}}{{sfn|Lyman|2021|p=46}}

Parallel to the theological controversy between Alexander and Arius was the [[Melitian schism]] in the Alexandrian church. [[Melitius of Lycopolis|Melitius]], bishop of [[Lycopolis]], had acted in the stead of the imprisoned bishop [[Peter I of Alexandria]] during the [[Diocletianic Persecution]], but after Peter's death in 311 refused to give up his right to ordain clergy or recognize the authority of Peter's successors [[Pope Achillas of Alexandria|Achillas]] or Alexander.{{sfn|Edwards|2006|p=557}}{{sfn|Brent|2022}}

=== Constantine and the calling of the council ===
In 324, the western Roman emperor Constantine defeated the eastern emperor [[Licinius]] and became the sole ruler of the Roman Empire.{{sfn|Cameron|2007|p=542}} It was at this time that{{mdash}}likely from Eusebius of Nicomedia{{mdash}}he became aware of the controversy between Alexander and Arius.{{sfn|Van Dam|2021|p=25}} Constantine wrote a letter to the two, urging them to end their dispute and reconcile.{{sfn|Hanson|1988|p=137}} This was not Constantine's first direct involvement in ecclesiastical controversy; he had previously attempted to resolve a schism over [[Donatism]] in North Africa, first appointing [[Pope Miltiades|Miltiades, Bishop of Rome]], to hear the dispute (with the instruction "I do not wish you to leave schism or division of any kind anywhere.") and then calling the [[Synod of Arles#Council of Arles in 314|Council of Arles]].{{sfn|Drake|2021|pp=113–114}}

Constantine's letter was carried to Alexandria by [[Hosius of Corduba|Bishop Hosius of Corduba]] as his representative. Hosius apparently then presided over a synod at Alexandria concerning the date of Easter, before calling a council of Eastern bishops in Antioch. This council endorsed Alexander's position and issuing a statement of faith that held that the Son was "begotten not from non-existence, but from the Father, not as made, but as genuine product" and contained anathemas against Arius.{{sfn|Hanson|1988|pp=146–151}}{{sfn|Lyman|2021|p=46}} Eusebius of Caesaria was also temporarily excommunicated because of his contention that the Father and the Son were of two different natures.{{sfn|Ayres|2004|p=16}}{{sfn|Edwards|2006|pp=557–558}}

Hosius prompted Constantine to call for a council.<ref>{{cite web | title=Hosius of Córdoba &#124; Christianity, Visigoths, Reformer &#124; Britannica | url=https://www.britannica.com/biography/Hosius-of-Cordoba }}</ref><ref>{{cite web | title=Bishop Osius (256-357?) | date=12 July 2023 | url=https://www.omnesmag.com/en/signatures/bishop-osio/ }}</ref><ref>{{cite web | title=Pope Silvester & the Council of Nicaea (Vs. James White) | date=12 January 2017 | url=https://www.patheos.com/blogs/davearmstrong/2017/01/pope-silvester-council-nicaea-vs-james-white.html }}</ref>
The bishops were then to assemble in [[Ancyra]] in Asia Minor for a "great and hierarchic council", either at their own impetus or Constantine's command. Constantine moved the council to [[Nicaea]] in Bithynia, a venue that would allow him to attend personally (due to its proximity to his capital at [[Nicomedia]]) and would allow easier access for bishops from throughout the empire.<ref>{{Citation |last=Drake |first=Harold A. |title=Church and Empire |date=2008-09-04 |work=The Oxford Handbook of Early Christian Studies |pages=446–464 |editor-last=Harvey |editor-first=Susan Ashbrook |url=https://academic.oup.com/edited-volume/42623/chapter-abstract/357712085?redirectedFrom=fulltext |access-date=2025-03-14 |publisher=Oxford University Press |doi=10.1093/oxfordhb/9780199271566.003.0023 |isbn=978-0-19-927156-6 |editor2-last=Hunter |editor2-first=David G.|url-access=subscription }}</ref>{{sfn|Hanson|1988|pp=152–153}} The emperor had also planned a commemoration of the twentieth year of his reign in Nicaea.{{sfn|Drake|2021|p=120}}

===Attendance===
The expenses of the council, including the travel of the bishops, were paid by the imperial treasury.{{sfn|Jacobs|2021|p=77}} Contemporary reports of attendance range from 250 to 300, with the figure of 318 given by Athanasius of Antioch becoming traditionally accepted.{{sfn|Hanson|1988|pp=155–156}} 318 is also the number of members of [[Abraham]]'s household given in the [[Book of Genesis]].{{sfn|Edwards|2006|p=558}} Lists of signatories to the final decisions of the council contain 200–220 names.{{sfn|Gwyn|2021|p=93}} With presbyters and deacons attending each bishop, the total attendance may have been between 1200 and 1900.{{sfn|Jacobs|2021|p=77}} Most of the bishops were eastern, with about twenty from Egypt and Libya, another fifty from Palestine and Syria, and more than one hundred from Asia
Minor.{{sfn|Edwards|2006|p=558}} One bishop each from Persia and Scythia were present.{{sfn|Gwyn|2021|p=93}} The few western attendees were Hosius, [[Caecilianus|Caecilianus of Carthage]], [[Nicasius of Die]], [[Marcus of Calabria]], [[Domnus of Pannonia]], and Victor and Vicentius, two presbyters representing [[Pope Sylvester I|Bishop Sylvester of Rome]]. Of the eastern bishops, the principal supporters of Arius were Eusebius of Nicomedia, Eusebius of Caesarea, Menophantus of [[Metropolis of Ephesus|Ephesus]], [[Patrophilus of Scythopolis]], Narcissus of [[Irenopolis (Cilicia)#Bishopric|Neronias]], Theonas of Marmarike, [[Secundus of Ptolemais]], and [[Theognis of Nicaea]]. The principal anti-Arians included Alexander of Alexandria, [[Eustathius of Antioch]], [[Marcellus of Ancyra]] and [[Macarius of Jerusalem]].{{sfn|Hanson|1988|pp=156–157}}

The council was held in Nicea's imperial palace.{{sfn|Jacobs|2021|p=78}} The bishops most likely assembled in a rectangular [[basilica]] hall based on Eusebius of Caearea's description.{{sfn|Jacobs|2021|pp=82–86}}

==Overview==
Constantine opened the council with a formal entrance after the bishops arrived, with Eusebius describing him as "like some heavenly angel of God, his bright mantle shedding lustre like beams of light, shining with the fiery radiance of a purple robe, and decorated with the dazzling brilliance of gold and precious stones." He then gave an opening speech in Latin (rather than the Greek spoken by most of the attendees).{{sfn|Drake|2021|p=124}} Fifth-century church historian [[Socrates of Constantinople]] gives the date of the opening as 20 May 325, though it may have been later in June.{{sfn|Gwyn|2021|pp=96–97}}{{sfn|Barnes|1981|pp=215, 380}}

It is most likely that Hosius presided over the council's debates and proceedings as Constantine's representative.{{sfn|Gwyn|2021|p=98}}{{sfn|Hanson|1988|p=154}} Constantine did join in the debates of the council (in Greek), but did not see himself as a voting member as he was not a bishop.{{sfn|Gwyn|2021|p=98}} No detailed ''acta'' of the council exist as they do for later councils, so the exact sequence of the council's debates is uncertain.{{sfn|Hanson|1988|pp=157–158}} Church councils at the time were modeled after the proceedings of the [[Roman Senate]], with the presiding officer having a large degree of control, and participants speaking in turn based on hierarchy.{{sfn|Drake|2021|p=125}} Probably the first matter considered was the status of Eusebius of Caesarea and the other bishops excommunicated at Antioch, as this would determine whether they could participate in the rest of the council. According to Eusebius, his profession of faith was accepted and he was restored.{{sfn|Gwyn|2021|pp=99–100}} An account by Eustathius of Antioch records a statement of faith by a Eusebius being rejected by the council, though this was likely Eusebius of Nicomedia.{{sfn|Hanson|1988|pp=160–161}}

A statement of faith based on earlier creeds was drafted (possibly by a smaller committee), and each line was debated by the council. All but two bishops subscribed to the final form of the creed as adopted.{{sfn|Gwyn|2021|p=101}} In addition to the Arian question, the council also considered the calculation of Easter, and adopted the Roman and Alexandrian method over the objection of several eastern bishops.{{sfn|Gwyn|2021|pp=102–104}} The bishops also agreed to a resolution on the Melitian schism and issued twenty canons.{{sfn|Gwyn|2021|pp=104–108}} The council closed in the first weeks of July, with the bishops invited to attend Constantine's celebration of his twentieth anniversary on the throne on 25 July. Both the bishops and the emperor issued letters recounting the councils' decisions to be circulated throughout the empire.{{sfn|Gwyn|2021|pp=108–109}}

== Ecumenical Council ==
The First Council of Nicaea was the first [[ecumenical council]] of the church. Nicaea "was the first time that any attempt had been made to summon a general council of the whole church at which, at least in theory, the church in every part of the Roman Empire should be represented".<ref>Hanson RPC, The Search for the Christian Doctrine of God: The Arian Controversy, 318-381. 1988, page 152</ref>

Derived from [[Koine Greek|Greek]] ({{langx|grc|οἰκουμένη|oikouménē|the inhabited one}}), "ecumenical" means "worldwide" but generally is assumed to be limited to the known inhabited Earth,<ref>{{citation |last=Danker |first=Frederick William |title=A Greek-English Lexicon of the New Testament and Other Early Christian Literature |url=https://books.google.com/books?id=hd7bZxvlbFsC |year=2000 |access-date=2014-02-24 |chapter=οἰκουμένη |edition=Third |location=Chicago |publisher=University of Chicago Press |isbn=978-0-226-03933-6 |author-link=Frederick William Danker}}</ref> and at this time in history is nearly synonymous with the [[Roman Empire]]. The earliest extant uses of the term for a council are [[Eusebius]]' ''Life of Constantine''<ref>{{harvnb|Vita Constantini|loc=Book 3, Chapter 6}}</ref> around 338, which states "he convoked an ecumenical council" ({{lang|grc|σύνοδον οἰκουμενικὴν συνεκρότει}}, {{Transliteration|grc|sýnodon oikoumenikḕn synekrótei}})<ref name="ReferenceA">{{harvnb|Ad Afros Epistola Synodica}}</ref> and a letter in 382 to [[Pope Damasus I]] and the Latin bishops from the [[First Council of Constantinople]].<ref>{{harvnb|SEC|pp=292–294}}</ref>

Historically significant as the first effort to attain [[consensus decision-making|consensus]] in the church through an [[legislature|assembly]] representing all of [[Christendom]],<ref name="Kieckhefer 1989">{{harvnb|Kieckhefer|1989}}</ref> the council was the first occasion where the technical aspects of [[Christology]] were discussed.<ref name="Kieckhefer 1989" /> Through it a precedent was set for subsequent general councils to adopt [[creed]]s and [[Canon (canon law)|canons]]. This council is generally considered the beginning of the period of the [[first seven ecumenical councils]] in the [[history of Christianity]].<ref>{{cite web |title=The First Seven Ecumenical Councils – MOLL-Y – The Method of Loci Learning – York |url=http://moll-y.co.uk/first-seven-ecumenical-councils/ |access-date=July 10, 2020}}</ref>

== Outcomes ==
=== Nicene Creed ===
{{Main|Nicene Creed}}[[File:Nicaea icon.jpg|thumb|upright|Icon depicting [[Constantine I|the Emperor Constantine]] and the bishops of the First Council of Nicaea (325) holding the [[Niceno-Constantinopolitan Creed|Niceno–Constantinopolitan Creed of 381]]]]

The council formulated a creed, a declaration and summary of the Christian faith. Several creeds were already in existence; many creeds were acceptable to the members of the council, including Arius. From earliest times, various creeds served as a means of identification for Christians, as a means of inclusion and recognition, especially at baptism. In Rome, for example, the [[Apostles' Creed]] was popular, especially for use in [[Lent]] and the Easter season. In the Council of Nicaea, one specific creed was used to define the Church's faith clearly, to include those who professed it, and to exclude those who did not.

The original Nicene Creed read as follows:

{{poemquote|We believe in one God, the Father almighty,
maker of all things visible and invisible;
And in one Lord, Jesus Christ, the Son of God,
begotten from the Father, only-begotten,
that is, from the substance of the Father,
God from God, light from light,
true God from true God, begotten not made,
of one substance with the Father,
through Whom all things came into being,
things in heaven and things on earth,
Who because of us men and because of our salvation came down,
and became incarnate and became man, and suffered,
and rose again on the third day, and ascended to the heavens,
and will come to judge the living and dead,
And in the Holy Spirit.
But as for those who say, There was when He was not,
and, Before being born He was not,
and that He came into existence out of nothing,
or who assert that the Son of God is of a different hypostasis or substance,
or created, or is subject to alteration or change
– these the Catholic and apostolic Church anathematizes.<ref name="creed">{{Cite web|url=https://earlychurchtexts.com/public/creed_of_nicaea_325.htm|title=Creed of Nicaea 325 – Greek and Latin Text with English translation|website=earlychurchtexts.com}}</ref>}}The creed was amended by the [[First Council of Constantinople]] in 381.

==== Distinctive elements ====
Some distinctive elements in the Nicene Creed, perhaps from the hand of Hosius of Cordova, were added, some specifically to counter the Arian point of view.<ref name="kelly1978">{{harvnb|Kelly|1978|loc=Chapter 9}}</ref><ref>{{harvnb|Loyn|1991|p=240}}</ref>

# Jesus Christ is described as "Light from Light, true God from true God", proclaiming his divinity.
# Jesus Christ is said to be "begotten, not made", asserting that he was not a mere creature, brought into being out of nothing, but the true Son of God, brought into being "from the substance of the Father".
# He is said to be "of one substance with the Father", proclaiming that although Jesus Christ is "true God" and God the Father is also "true God", they are "of one substance". The Greek term ''homoousios'', [[Consubstantiality|consubstantial]] (i.e. of the ''same'' substance) is ascribed by Eusebius of Caesarea to Constantine who, on this particular point, may have chosen to exercise his authority. The significance of this clause, however, is ambiguous as to the extent in which Jesus Christ and God the Father are "of one substance", and the issues it raised would be seriously controverted in the future.

==== Anathemas ====
At the end of the creed came a list of [[Anathema#Early Church|anathemas]], designed to repudiate explicitly the Arians' stated claims.

# The view that "there was once when he was not" was rejected to maintain the coeternity of the Son with the Father.
# The view that he was "mutable or subject to change" was rejected to maintain that the Son just like the Father was beyond any form of weakness or corruptibility, and most importantly that he could not fall away from absolute moral perfection.

Thus, instead of a baptismal creed acceptable to both the Arians and their opponents, the Council promulgated one which was clearly opposed to Arianism and incompatible with the distinctive core of their beliefs. The text of this profession of faith is preserved in a letter of Eusebius to his congregation, in Athanasius' works, and elsewhere. The [[Homoousian]]s (from the [[Koine Greek]] word translated as "of same substance" which was condemned at the [[Synods of Antioch#The Synods of Antioch in 264-269|Council of Antioch]] in 264–268) were supported by Constantine and Hosius and were able to advance the use of the term, thus the creed was accepted by the council.<ref>{{citation |pages=61–62 |last=Davis |first=Leo D. |title=The First Seven Ecumenical Councils (325-787): Their History and Theology |date=2017-03-15 |publisher=Liturgical Press |isbn=978-0-8146-8381-1 |language=en}}</ref>

==== Exiled ====
The emperor carried out his earlier statement: everybody who refused to endorse the creed would be [[exile]]d. Arius, Theonas, and Secundus refused to adhere to the creed and were thus exiled to [[Illyria]], in addition to being [[excommunication|excommunicated]]. The works of Arius were ordered to be confiscated and [[book burning|consigned to the flames]],<ref name=EB1911/> while his supporters were considered as "enemies of Christianity".{{sfn|Schaff|Schaff|1910|loc=Section 120}} Nevertheless, the controversy continued in various parts of the empire.<ref>{{harvnb|Lutz von Padberg|1998|p=26}}</ref>

=== Separation of Easter computation from Jewish calendar ===
The feast of Easter is linked to the Jewish [[Passover]] and Feast of Unleavened Bread, as Christians believe that the [[Crucifixion of Jesus|crucifixion]] and [[Resurrection of Jesus|resurrection]] of Jesus occurred at the time of those observances. As early as [[Pope Sixtus I]] in the 2nd century, some Christians had set Easter to a Sunday in the lunar month of [[Nisan]]. To determine which lunar month was to be designated as Nisan, Christians relied on the Jewish community. By the late 3rd century some Christians began to express dissatisfaction with what they took to be the disorderly state of the [[Hebrew calendar|Jewish calendar]]. They argued that contemporary Jews were identifying the wrong lunar month as the month of Nisan, choosing a month whose 14th day fell before the [[March equinox|spring equinox]].{{Sfn|Anatolius|loc=Book 7, Chapter 33}}

Christians, these thinkers argued, should abandon the custom of relying on Jewish informants and instead do their own computations to determine which month should be styled Nisan, setting Easter within this independently computed, Christian Nisan, which would always locate the festival after the equinox. They justified this break with tradition by arguing that it was in fact the contemporary Jewish calendar that had broken with tradition by ignoring the equinox and that in former times the 14th of Nisan had never preceded the equinox.{{Sfn|Chronicon Paschale}} Others felt that the customary practice of reliance on the Jewish calendar should continue, even if the Jewish computations were in error from a Christian point of view.{{Sfn|Panarion|loc=Book 3, Chapter 1, Section 10}}

The controversy between those who argued for independent computations and those who argued for continued reliance on the Jewish calendar was formally resolved by the council, which endorsed the independent procedure that had been in use for some time at Rome and Alexandria. Easter was henceforward to be a Sunday in a lunar month chosen according to Christian criteria—in effect, a Christian Nisan—not in the month of Nisan as defined by Jews.<ref name="ReferenceB" /> Those who argued for continued reliance on the Jewish calendar (called "protopaschites" by later historians) were urged to come around to the majority position. That they did not all immediately do so is revealed by the existence of sermons,{{Sfn|Chrysostom|p=47}} canons,{{Sfn|SEC|p=594}} and tracts{{Sfn|Panarion|loc=Book 3, Chapter 1}} written against the protopaschite practice in the late 4th century.

These two rules—independence of the Jewish calendar and worldwide uniformity—were the only rules for Easter explicitly laid down by the council. No details for the computation were specified; these were worked out in practice, a process that took centuries and [[Easter controversy|generated numerous controversies]], some of which remain unresolved. In particular, the Council did not seem to decree that Easter must fall on Sunday.{{Sfn|Sozomen|loc=Book 7, Chapter 18}} This was unnecessary as it resolved against the ''Quartodecimani'', who celebrated on any day of the week, in favour of the Churches who postponed the celebration to the following Sunday. See the extract from the ''Letter of the Council of Nicaea to the Egyptian Church'', cited above.

Nor did the Council decree that Easter must never coincide with Nisan 15 (the first Day of Unleavened Bread, now commonly called "Passover") in the Hebrew calendar. The Finnish Orthodox Church explains, "According to the definition of the Council of Nicaea in 325, Pascha is celebrated on the first Sunday after the full moon following the vernal equinox, but always after the Jewish Passover. The date of the vernal equinox was then defined as March 21."<ref>{{cite web|url=http://orthochristian.com/157576.html|last=Finnish Orthodox Church|title=Finnish church resolves to continue using Gregorian Paschalion|date=30 November 2023|accessdate=9 March 2024}}</ref> L'Huillier notes the success of this strategy - Orthodox Easter has never preceded Passover.{{Sfn|L'Huillier|1996|p=25}}

=== Resolution of the Melitian schism ===
The suppression of the Melitian schism, an early breakaway sect, was another important matter that came before the Council of Nicaea. [[Melitius of Lycopolis]], it was decided, should remain in his own city of [[Lycopolis]] in Egypt but without exercising authority or the power to ordain new clergy; he was forbidden to go into the environs of the town or to enter another diocese for the purpose of ordaining its subjects. Melitius retained his episcopal title, but the ecclesiastics ordained by him were to receive again the [[Christian laying on of hands|laying on of hands]], the ordinations performed by Melitius being therefore regarded as invalid. Clergy ordained by Melitius were ordered to yield precedence to those ordained by Alexander, and they were not to do anything without the consent of Bishop Alexander.<ref>{{harvnb|Leclercq|1911a}}</ref>

In the event of the death of a non-Melitian bishop or ecclesiastic, the vacant [[Episcopal see|see]] might be given to a Melitian, provided he was worthy and the popular election were ratified by Alexander. Melitius' episcopal rights and prerogatives were taken from him. These mild measures, however, were in vain; the Melitians joined the [[Arians]] and caused more dissension than ever, being among the worst enemies of Athanasius.<ref>{{citation |last=Kim |first=Young Richard |page=104 |title=The Cambridge Companion to the Council of Nicaea |date=2021-01-07 |publisher=Cambridge University Press |isbn=978-1-108-42774-6 |language=en}}</ref>

=== Promulgation of canon law ===
{{Main|Canon law|Collections of ancient canons|Promulgation (Catholic canon law)}}
The Council promulgated twenty new church laws, called ''[[Canon (canon law)|canons]]'' (though the exact number is subject to debate), that is, rules of discipline. The twenty as listed in the works of [[Nicene and Post-Nicene Fathers]] are as follows:<ref>{{harvnb|Canons}}</ref>

# prohibition of self-[[castration]] for clergy
# establishment of a minimum term for [[catechumen]]s (persons studying for baptism)
# prohibition of a man and a woman who have both taken [[Religious vows|vows of chastity]] to live together in a chaste and non-legalized partnership (the so-called ''virgines subintroductae'', who practiced [[syneisaktism]])
# ordination of a bishop in the presence of at least three provincial bishops<ref name=EB1911/> and confirmation by the [[metropolitan bishop]]
# provision for two provincial [[synod]]s to be held annually
# confirmation of ancient customs giving jurisdiction over large regions to the bishops of Alexandria, Rome, and Antioch
# recognition of the honorary rights of the see of [[Jerusalem in Christianity|Jerusalem]]
# provision for agreement with the [[Novatianism|Novatianists]], an early sect
# elders who had been ordained without sufficient examination were not to be recognized
# elders who had lapsed but had not been found out were to be deposed
# mercy was enjoined toward those who had lapsed without compulsion, even though it was recognized that they did not deserve it
# those who had left the military but later sought out to be restored to their military position were to be excommunicated; depending on the sincerity of their repentance, they could be readmitted to communion earlier
# those who were fulfilling [[penance]] could receive communion if they were dying, but if they got well again, they were to finish their penance
# catechumens who lapsed were to have three years as hearers before being allowed to become catechumens again
# bishops, presbyters, and deacons were not to wander into neighboring cities to officiate
# clergy who refused to return to their home church were to be excommunicated, and the ordinations of those who were ordained by these wandering clergy were to be considered null and void
# prohibition of [[usury]] among the clergy
# precedence of bishops and presbyters before deacons in receiving the [[Eucharist]] (Holy Communion)
# declaration of the invalidity of [[baptism]] by [[Paul of Samosata|Paulian heretics]]
# prohibition of kneeling on Sundays and during the [[Pentecost]] (the fifty days commencing on Easter). Standing was the normative posture for prayer at this time, as it still is among the Eastern Christians. Kneeling was considered most appropriate to penitential prayer, as distinct from the festive nature of Eastertide and its remembrance every Sunday. The canon was designed only to ensure uniformity of practice at the designated times.

== Effects ==
{{see also|Nicene Christianity}}
[[File:COUNCIL OF NICEA Fresco in the Sistine Salon Vatican t.jpg|thumb|upright=1.25|A fresco depicting the First Council of Nicaea at the [[Vatican City|Vatican]]'s Sistine Salon]]
In the short-term, the Council did not completely solve the problems it was convened to discuss, and a period of conflict and upheaval continued for some time. Constantine was succeeded by two Arian emperors in the Eastern Empire: his son, [[Constantius II]], and [[Valens]]. Valens could not resolve the outstanding ecclesiastical issues and unsuccessfully confronted [[Basil of Caesarea|St. Basil]] over the Nicene Creed.<ref>{{cite magazine |date=February 1968|title=Heroes of the Fourth Century |magazine=Word Magazine |publisher=Antiochian Orthodox Christian Archdiocese of North America |pages=15–19 |url=http://www.orthodoxresearchinstitute.org/articles/patrology/heroes_of_4th_century_pt2.htm}}</ref>

Pagan powers within the empire sought to maintain and at times re-establish paganism into the seat of the emperor (see [[Arbogast (magister militum)|Arbogast]] and [[Julian the Apostate]]). Arians and Meletians soon regained nearly all of the rights they had lost, and consequently Arianism continued to spread and be a subject of debate within the Church during the remainder of the 4th century. Almost immediately, Eusebius of Nicomedia, an Arian bishop and cousin to Constantine I, used his influence at court to sway Constantine's favor from the proto-orthodox Nicene bishops to the Arians.<ref name="Davis 1983 77">{{harvnb|Davis|1983|p=77}}</ref>

Eustathius of Antioch was deposed and exiled in 330. Athanasius, who had succeeded Alexander as Bishop of Alexandria, was deposed by the [[First Synod of Tyre]] in 335, and Marcellus of Ancyra followed him in 336. Arius returned to Constantinople to be readmitted into the Church but died shortly before he could be received. Constantine died the next year, after finally receiving baptism from Arian Bishop Eusebius of Nicomedia, and "with his passing the first round in the battle after the Council of Nicaea was ended".<ref name="Davis 1983 77" />

== Role of Constantine ==
{{See also|Constantine the Great and Christianity}}
Christianity had only recently been legalised in the empire, the [[Diocletianic Persecution]] having ended in 311 under [[Galerius]]. Although Galerius stopped the Persecution, Christianity was not legally protected until 313, when the emperors Constantine and [[Licinius]] agreed to what became known as the [[Edict of Milan]], guaranteeing Christians legal protection and tolerance. However, Nicene Christianity did not become the [[state religion]] of the [[Roman Empire]] until the [[Edict of Thessalonica]] in 380. In the meantime, paganism remained legal and present in public affairs. Constantine's coinage and other official motifs, until the Council of Nicaea, had affiliated him with the pagan cult of [[Sol Invictus]]. At first, Constantine encouraged the construction of new temples<ref>Gerberding, R. and J. H. Moran Cruz, ''Medieval Worlds'' (New York: Houghton Mifflin Company, 2004) p. 28.</ref> and tolerated [[Religion in ancient Rome#Sacrifice|traditional sacrifices]].<ref>Peter Brown, ''The Rise of Christendom'' 2nd edition (Oxford, Blackwell Publishing, 2003) p. 60.</ref> Later in his reign, he gave orders for the [[pillaging]] and the tearing down of [[Roman temple]]s.<ref>R. MacMullen, ''Christianizing The Roman Empire A.D. 100–400'', Yale University Press, 1984, {{ISBN|0-300-03642-6}}</ref><ref>"A History of the Church", [[Philip Hughes (historian)|Philip Hughes]], Sheed & Ward, rev ed 1949, vol I chapter 6.[http://www.ewtn.com/library/CHISTORY/HUGHHIST.TXT]</ref><ref>Eusebius Pamphilius and [[Philip Schaff|Schaff, Philip]] (Editor) and McGiffert, Rev. Arthur Cushman, PhD (Translator) [http://www.ccel.org/ccel/schaff/npnf201.txt ''NPNF2-01. Eusebius Pamphilius: Church History, Life of Constantine, Oration in Praise of Constantine''] {{Webarchive|url=https://web.archive.org/web/20180417033355/http://www.ccel.org/ccel/schaff/npnf201.txt |date=17 April 2018 }} quote: "he razed to their foundations those of them which had been the chief objects of superstitious reverence".</ref>

Constantine's role regarding Nicaea was that of supreme civil leader and authority in the empire. As Emperor, the responsibility for maintaining civil order was his, and he sought that the Church be of one mind and at peace. When first informed of the unrest in Alexandria due to the Arian disputes, he was "greatly troubled" and, "rebuked" both Arius and Bishop [[Pope Alexander I of Alexandria|Alexander]] for originating the disturbance and allowing it to become public.<ref name="sozomen1">{{harvnb|Sozomen|loc=Book 1, Chapter 16}}</ref> Aware also of "the diversity of opinion" regarding the celebration of Easter and hoping to settle both issues, he sent the "honored" Bishop [[Hosius of Corduba|Hosius of Cordova]] (Hispania) to form a local church council and "reconcile those who were divided".<ref name="sozomen1" /> When that embassy failed, he turned to summoning a synod at Nicaea, inviting "the most eminent men of the churches in every country".<ref>{{harvnb|Sozomen|loc=Book 1, Chapter 17}}</ref>

Constantine assisted in assembling the council by arranging that travel expenses to and from the bishops' [[episcopal see]]s, as well as lodging at Nicaea, be covered out of public funds.<ref name="theodoret1">{{harvnb|Theodoret|loc=Book 1, Chapter 6}}</ref> He also provided and furnished a "great hall ... in the palace" as a place for discussion so that his guests "should be treated with becoming dignity".<ref name="theodoret1" /> In addressing the opening of the council, he "exhorted the Bishops to unanimity and concord" and called on them to follow the Holy Scriptures with: "Let, then, all contentious disputation be discarded; and let us seek in the divinely-inspired word the solution of the questions at issue."<ref name="theodoret1" />

Thereupon, the debate about Arius and church doctrine began. "The emperor gave patient attention to the speeches of both parties" and "deferred" to the decision of the bishops.<ref>{{harvnb|Sozomen|loc=Book 1, Chapter 20}}</ref> The bishops first pronounced Arius' teachings to be anathema, formulating the creed as a statement of correct doctrine. When Arius and two followers refused to agree, the bishops pronounced clerical judgement by excommunicating them from the Church. Respecting the clerical decision, and seeing the threat of continued unrest, Constantine also pronounced civil judgement, banishing them into exile. This was the beginning of the practice of using secular power to establish doctrinal orthodoxy within Christianity, an example followed by all later Christian emperors, which led to a circle of Christian violence, and of Christian resistance couched in terms of martyrdom.<ref>There is no crime for those who have Christ; religious violence in the Roman Empire. Michael Gaddis. University of California Press 2005. p. 340.{{ISBN|978-0-520-24104-6}}</ref>

== Misconceptions ==

=== Biblical canon ===
{{Main|Development of the Christian Biblical canon}}

There is no record of any discussion of the [[biblical canon]] at the council.<ref>John Meade, "[https://ps.edu/council-nicaea-biblical-canon/ The Council of Nicaea and the Biblical Canon]" and {{harvnb|Ehrman|2004|pp=15–16, 23, 93}}</ref> The development of the biblical canon was nearly complete (with exceptions known as the [[Antilegomena]], written texts whose authenticity or value is disputed) by the time the [[Muratorian fragment]] was written.<ref>{{harvnb|McDonald & Sanders|2002|loc=Apendex D2, Note 19}}</ref> The main source of the idea that the canon was created at the Council of Nicaea seems to be [[Voltaire]], who popularised a story that the canon was determined by placing all the competing books on an altar during the council and then keeping the ones that did not fall off. The original source of this "fictitious anecdote" is the ''[[Synodicon Vetus]]'',<ref>{{cite book |title=Ecce homo!: An Eighteenth Century Life of Jesus |others=Critical Edition and Revision of George Houston's Translation from the French |url=https://books.google.com/books?id=ZrDnBQAAQBAJ |author=Paul T. d' Holbach |author-link=Baron d'Holbach |editor=Andrew Hunwick |year=1995 |location=Berlin, New York |publisher=Walter de Gruyter & Co. |isbn=978-3-11-081141-4 |pages=48–49}}</ref> a pseudo-historical account of early Church councils from 887.<ref>A summary of the case can be found at [http://www.tertullian.org/rpearse/nicaea.html The Council of Nicaea and the Bible].</ref>

In 331, [[Fifty Bibles of Constantine|Constantine commissioned fifty Bibles]] for the use of the Bishop of Constantinople, but little else is known (in fact, it is not even certain whether his request was for fifty copies of the entire Old and New Testaments, only the New Testament, or merely the Gospels). Some scholars believe that this request provided motivation for canon lists. In [[Jerome]]'s ''Prologue to Judith'', he claims that the [[Book of Judith]] was "found by the Nicene Council to have been counted among the number of the Sacred Scriptures".<ref>{{harvnb|Preface to Tobit and Judith}}</ref> However, modern scholars such as Edmon Gallagher have doubted that this indicates any canon selection in the council.<ref>{{cite web |url=https://www.academia.edu/14345165 |title="Why Did Jerome Translate Tobit and Judith?" Harvard Theological Review 108 (2015): 356–75.|last=Gallagher |first=Edmon|date=2015 |website=academia.edu |pages=369–370|access-date= November 26, 2022}}</ref>

=== Trinity ===
The Council of Nicaea dealt primarily with the issue of the [[deity of Christ]]. The term "Trinity" was already in use, with the earliest existing reference being by [[Theophilus of Antioch]] (AD 115–181), referring to Theos, the Logos, and Sophia<ref>{{Cite web |title=Philip Schaff: Fathers of the Second Century: 0107=101 – Christian Classics Ethereal Library |url=https://ccel.org/ccel/schaff/anf02/anf02/Page_101.html |access-date=2023-04-27 |website=ccel.org}}</ref> (Father, Son, and Holy Spirit, as the Holy Spirit was referred to by several Church fathers), though many scholars believe that the way the term was used indicates that it was known previously to his readers. Also, over a century before, the term "[[Trinity]]" ({{lang|grc|Τριάς}} in Greek; {{lang|la|trinitas}} in Latin) was used in the writings of [[Origen]] and [[Tertullian]], and a general notion of a "divine three", in some sense, was expressed in the 2nd-century writings of [[Polycarp]], [[Ignatius of Antioch|Ignatius]], and [[Justin Martyr]]. In Nicaea, questions regarding the Holy Spirit were left largely unaddressed until after the relationship between the Father and the Son was settled around the year 362.<ref>{{harvnb|Fairbairn|2009|pp=46–47}}</ref> The doctrine in a more full-fledged form was not formulated until the [[Council of Constantinople (381)|Council of Constantinople]] in 381<ref>{{harvnb|Socrates|loc=Book 2, Chapter 41}}</ref> and a final form formulated primarily by [[Gregory of Nyssa]].<ref>{{Cite book|last1=Schaff|first1=Philip|url=https://books.google.com/books?id=AIAXAAAAYAAJ&pg=PA477|title=A Select Library of Nicene and Post-Nicene Fathers of the Christian Church: Gregory of Nyssa: Dogmatic treatises, etc. 1893|last2=Wace|first2=Henry|date=1893|publisher=Christian literature Company|language=en}}</ref>

=== Constantine ===
While Constantine had sought a unified church after the council, he did not force the [[homoousian]] view of Christ's nature on the council. Constantine did not commission any Bibles at the council. Despite Constantine's sympathetic interest in the Church, he was not baptized until some 11 or 12 years after the council, putting off baptism as long as he did so as to be absolved from as much sin as possible.<ref>Marilena Amerise, 'Il battesimo di Costantino il Grande."</ref>

== Disputed matters ==
{{See also|Primacy of the Roman pontiff|East–West Schism}}

According to Protestant theologian [[Philip Schaff]]: "The Nicene fathers passed [the sixth] canon not as introducing anything new, but merely as confirming an existing relation on the basis of church tradition; and that, with special reference to Alexandria, on account of the troubles existing there. Rome was named only for illustration; and Antioch and all the other eparchies or provinces were secured their admitted rights. The [[Episcopal see|bishoprics]] of [[Early centers of Christianity#Alexandria|Alexandria]], [[Early centers of Christianity#Rome|Rome]], and [[Early centers of Christianity#Antioch|Antioch]] were placed substantially on equal footing." Thus, according to Schaff, the Bishop of Alexandria was to have jurisdiction over the provinces of Egypt, Libya and the Pentapolis, just as the Bishop of Rome had authority "with reference to his own diocese."<ref>{{harvnb|Schaff|Schaff|1910|pp=275–276}}</ref>

However, according to Fr. James F. Loughlin, there is an alternative Catholic interpretation. It involves five different arguments "drawn respectively from the grammatical structure of the sentence, from the logical sequence of ideas, from Catholic analogy, from comparison with the process of formation of the Byzantine Patriarchate, and from the authority of the ancients"<ref name="Loughlin 1880">{{harvnb|Loughlin|1880}}</ref> in favor of an alternative understanding of the canon. According to this interpretation, the canon shows the role the Bishop of Rome had when he, by his authority, confirmed the jurisdiction of the other patriarchs—an interpretation which is in line with the Catholic understanding of the Pope. Thus, the Bishop of Alexandria presided over Egypt, Libya and the Pentapolis,<ref name="EB1911">{{cite EB1911 |wstitle=Nicaea, Council of |volume=19 |pages=640–642 |first=Carl Theodor |last=Mirbt}}</ref> while the Bishop of Antioch "enjoyed a similar authority throughout the great diocese of Oriens," and all by the authority of the Bishop of Rome. To Loughlin, that was the only possible reason to invoke the custom of a Roman Bishop in a matter related to the two metropolitan bishops in Alexandria and Antioch.<ref name="Loughlin 1880" />

However, Protestant and Catholic interpretations have historically assumed that some or all of the bishops identified in the canon were presiding over their own dioceses at the time of the Council—the Bishop of Rome over the Diocese of Italy, as Schaff suggested, the Bishop of Antioch over the Diocese of Oriens, as Loughlin suggested, and the Bishop of Alexandria over the Diocese of Egypt, as suggested by [[Karl Josef von Hefele]]. According to Hefele, the council had assigned to Alexandria, "the whole (civil) Diocese of Egypt."<ref>{{cite book|last1=von Hefele|first1=Karl|title=Conciliengeschichte, v. 1|date=1855|publisher=Herder|location=Freiburg im Breisgau, Baden-Württemberg, Germany|page=373}}</ref> Yet those assumptions have since been proven false. At the time of the council, the [[Diocese of Egypt]] did exist but was known as the Diocese of Alexandria, so the council could have assigned it to Alexandria. Antioch and Alexandria were both located within the civil Diocese of Oriens, Antioch being the chief metropolis, but neither administered the whole. Likewise, Rome and Milan were both located within the civil Diocese of Italy, Milan being the chief metropolis.<ref>{{cite web|last1=Athanasius of Alexandria|title=Historia Arianorum, Part IV, chapter 36|url=http://www.newadvent.org/fathers/28154.htm|access-date=22 June 2016}}</ref><ref>{{cite web|last1=Athanasius of Alexandria|title=Apologia de Fuga, chapter 4|url=http://www.newadvent.org/fathers/2814.htm|access-date=22 June 2016}}</ref>

This geographic issue related to Canon 6 was highlighted by Protestant writer Timothy F. Kauffman, as a correction to the anachronism created by the assumption that each bishop was already presiding over a whole diocese at the time of the council.<ref>{{cite journal|last1=Kauffman|first1=Timothy F.|title=Nicæa and the Roman Precedent|journal=The Trinity Review|date=May–June 2016|issue=334, 335|url=http://trinityfoundation.org/PDF/The%20Trinity%20Review%20334%20Nica%20and%20the%20Roman%20Precedent%20Kauffman.pdf |archive-url=https://web.archive.org/web/20160812085230/http://trinityfoundation.org/PDF/The%20Trinity%20Review%20334%20Nica%20and%20the%20Roman%20Precedent%20Kauffman.pdf |archive-date=2016-08-12 |url-status=live|access-date=22 June 2016}}</ref> According to Kauffman, since Milan and Rome were both located within the Diocese of Italy, and Antioch and Alexandria were both located within the Diocese of Oriens, a relevant and "structural congruency" between Rome and Alexandria was readily apparent to the gathered bishops: both had been made to share a diocese of which neither was the chief metropolis. Rome's jurisdiction within Italy had been defined in terms of several of the city's adjacent provinces since Diocletian's reordering of the empire in 293, as the earliest Latin version of the canon indicates.<ref>{{cite book|last1=Turner|first1=Cuthberthus Hamilton|title=Ecclesiae Occidentalis monumenta iuris antiquissima, vol. 1|date=1899|publisher=Oxonii, E Typographeo Clarendoniano|page=120}}</ref>

That provincial arrangement of Roman and Milanese jurisdiction within Italy therefore was a relevant precedent, and provided an administrative solution to the problem facing the Council—namely, how to define Alexandrian and Antiochian jurisdiction within the Diocese of Oriens. In canon 6, the Council left most of the diocese under Antioch's jurisdiction, and assigned a few provinces of the diocese to Alexandria, "since the like is customary for the Bishop of Rome also."<ref>{{cite web|last1=First Council of Nicæa|title=Canon 6|url=http://www.newadvent.org/fathers/3801.htm|website=The First Council of Nicæa|access-date=22 June 2016}}</ref>

==Primary sources==
There are no conciliar acts. The main historical sources are: the ''[[Ecclesiastical History (Eusebius)|Ecclesiastical History]]'' by [[Eusebius of Caesarea]], the ''History of the First Council of Nicaea'' by [[Gelasius of Cyzicus]], and three orations of Athanasios ''Against the Arians'' and two epistles, one written in 350-351, concerning the decisions of the Council of Nicaea,<ref>The ''Epistula de decretis nicaenae synodi'', in which Athanasius defends the terminology of the council. Cf. {{Cite journal|author=Dudzik, Pavel|date=2014-01-05|title=Nicene terminology defended by Athanasius of Alexandria in "De Decretis Nicaenae synodi" and the possible influence of Eusebius' "Epistula ad Caesarienses"|journal=[[Vox Patrum]]|volume=61|pages=123–135|access-date=2024-06-11|doi=10.31743/vp.3613|url=https://czasopisma.kul.pl/index.php/vp/article/view/3613 | issn=0860-9411|doi-access=free}}</ref> which includes the [[Nicene creed]], and the other one ''On the Events of the Councils in [[Rimini|Ariminum]] and [[Seleucia]]''. Other primary sources are the following: ''Ecclesiastical History''<sub>[[w:it:Storia ecclesiastica (Socrate Scolastico)|it]]</sub> by [[Socrates Scholasticus]] and those of [[Sozomen]], [[Theodoret|Theodoret of Cirrhus]], and [[Rufinus of Aquileia]]. Theological aspects are also dealt with by [[Basil of Caesarea]], [[Gregory of Nyssa]], and [[Gregory of Nazianzus]].<ref>{{Cite web|author=Moutafov, Emmanuel|title=First Ecumenical Council of Nicea, 325|date=8 August 2013 |access-date=2024-05-28|url=https://www.academia.edu/4200703}}</ref> Primary sources are collected on the [[Wisconsin Lutheran College]]'s Fourth Century Christianity website.<ref name="CouncilFourthCentury">{{cite web |title=Council of Nicaea (AD 325) |url=https://www.fourthcentury.com/council-of-nicaea-ad-325/ |website=Fourth-Century Christianity |publisher=[[Wisconsin Lutheran College]] |access-date=12 May 2025}}</ref>

== See also ==
* [[List of attendees and signatories of the First Council of Nicaea]]
* [[Ancient church councils (pre-ecumenical)]], church councils before the First Council of Nicaea

== References ==
{{Reflist|30em}}

== Bibliography ==

=== Primary sources ===
Note: NPNF2 = {{citation |editor1-last=Schaff |editor1-first=Philip |editor-link1=Philip Schaff |editor2-last=Wace |editor2-first=Henry |title=Nicene and Post-Nicene Fathers |url=http://www.ccel.org/fathers.html |series=Second Series |publisher= Christian Classics Ethereal Library |ref=none}}, see also [[Nicene and Post-Nicene Fathers]]
* {{Cite book |last= |title=Fontes Nicaenae Synodi: The Contemporary Sources for the Study of the Council of Nicaea (304–337) |publisher=[[Brill Publishers]] |year=2024 |isbn=978-3-657-79640-3 |editor-last=Fernández |editor-first=Samuel}}
* {{citation|title=Eusebius Pamphilius: Church History, Life of Constantine, Oration in Praise of Constantine|url=http://www.ccel.org/ccel/schaff/npnf201.iii.html|series=NPNF2|volume=1|access-date=2014-02-24}}
** {{citation|author=Anatolius of Laodicea|author-link=Anatolius of Laodicea|title=The Ecclesiastical History of Eusebius|chapter-url=http://www.ccel.org/ccel/schaff/npnf201.iii.xii.xxxiii.html|chapter=''Paschal Canons'' quoted by Eusebius|ref={{harvid|Anatolius}}}}
** {{citation|author=Eusebius Pamphilius|author-link=Eusebius|title=The Life of Constantine [Vita Constantini].|url=http://www.ccel.org/ccel/schaff/npnf201.iv.vi.html|ref={{harvid|Vita Constantini}}}}
* {{citation|title=Socrates and Sozomenus Ecclesiastical Histories|url=http://www.ccel.org/ccel/schaff/npnf202.html|series=NPNF2|volume=2|ref={{harvid|Socrates}}}}
** {{citation|author=Socrates of Constantinople|author-link=Socrates of Constantinople|title=The Ecclesiastical History of Socrates Scholasticus|url=http://www.ccel.org/ccel/schaff/npnf202.ii.html|access-date=2014-02-24}}
** {{citation|author=Sozomen|author-link=Sozomen|title=The Ecclesiastical History of Sozomen|url=http://www.ccel.org/ccel/schaff/npnf202.iii.html}}
* {{citation|title=Theodoret, Jerome, Gennadius, and Rufinus: Historical Writings|url=http://www.ccel.org/ccel/schaff/npnf202.iii.html|series=NPNF2|volume=3|access-date=2014-02-24}}
** {{citation|author=Constantine the Great|author-link=Constantine the Great|title=The Ecclesiastical History of Theodoret|chapter-url=http://www.ccel.org/ccel/schaff/npnf203.iv.viii.i.x.html|chapter=''Constantinus Augustus to the Churches'' quoted by Theodoret|access-date=2014-02-24}}
** {{citation|author=Eustathius of Antioch|author-link=Eustathius of Antioch|title=The Ecclesiastical History of Theodoret|chapter-url=http://www.ccel.org/ccel/schaff/npnf203/Page_45.html|chapter=''A Letter to the African Bishops'' quoted by Theodoret|access-date=2014-02-24}}
** {{citation|author=Theodoret of Cyrus|author-link=Theodoret of Cyrus|title=The Ecclesiastical History of Theodoret|url=http://www.ccel.org/ccel/schaff/npnf203.iv.viii.html|ref={{harvid|Theodoret}}}}
* {{citation|title=Athanasius: Select Works and Letters|url=http://www.ccel.org/ccel/schaff/npnf204.html|series=NPNF2|volume=4|access-date=2014-02-24}}
** {{citation|author=Athanasius of Alexandria|author-link=Athanasius of Alexandria|title=De Decretis|url=http://www.ccel.org/ccel/schaff/npnf204.xiv.ii.html|trans-title=Defence of the Nicene Definition|access-date=2014-02-24}}
** {{citation|author=Athanasius of Alexandria|author-link=Athanasius of Alexandria|title=Ad Afros Epistola Synodica|url=http://www.ccel.org/ccel/schaff/npnf204.xxiv.html|trans-title=Synodal Letter to the Bishops of Africa|ref={{harvid|Ad Afros Epistola Synodica}}}}
** {{citation|author=Eusebius Pamphilus|author-link=Eusebius Pamphilus|title=Letter of Eusebius of Cæsarea to the people of his Diocese|url=http://www.ccel.org/ccel/schaff/npnf204.ix.ii.html|access-date=2014-02-24}}
* {{citation|title=Jerome: The Principal Works of St. Jerome|url=http://www.ccel.org/ccel/schaff/npnf206|series=NPNF2|volume=6|access-date=2014-02-24}}
** {{citation|author=Jerome|author-link=Jerome|title=Prefaces to the Books of Tobit and Judith|url=http://www.ccel.org/ccel/schaff/npnf206.vii.iii.xx.html|ref={{harvid|Preface to Tobit and Judith}}}}
* {{citation|title=The Seven Ecumenical Councils|url=http://www.ccel.org/ccel/schaff/npnf214.html|series=NPNF2|volume=14|ref={{harvid|SEC}}}}
** {{citation|title=The Nicene Creed|url=http://www.ccel.org/ccel/schaff/npnf214.vii.iii.html|access-date=2014-02-24}}
** {{citation|title=The Canons of the 318 Holy Fathers Assembled in the City of Nice, in Bithynia|url=http://www.ccel.org/ccel/schaff/npnf214.vii.vi.i.html|ref={{harvid|Canons}}}}
** {{citation|author=Athanasius of Alexandria|author-link=Athanasius of Alexandria|title=The Synodal Letter|url=http://www.ccel.org/ccel/schaff/npnf214.vii.ix.html|access-date=2014-02-24}}
** {{citation|author=Constantine the Great|author-link=Constantine the Great|title=The Life of Constantine|chapter-url=http://www.ccel.org/ccel/schaff/npnf214.vii.x.html|chapter=''On the Keeping of Easter'' quoted by Eusebius|ref={{harvid|On the Keeping of Easter}}}}
* {{citation|title=Chronicon Paschale|trans-title=Paschal Chronicle|ref={{harvid|Chronicon Paschale}}|title-link=Chronicon Paschale}}
* {{citation|title=Pentecostarion|url=http://www.anastasis.org.uk/FathVes.htm|access-date=22 February 2014|date=3 November 2008|publisher=Archdiocese of Thyateira and Great Britain|ref={{harvid|Pentecostarion}}|archive-url=https://web.archive.org/web/20160430004400/http://anastasis.org.uk/FathVes.htm|archive-date=30 April 2016|url-status=dead}}
* {{citation|last1=Chrysostom|first1=John|author-link1=John Chrysostom|last2=Harkins|first2=Paul W (trans)|title=Discourses Against Judaizing Christians|url=https://books.google.com/books?id=JXtTCq7V_0MC|series=The Fathers of the Church|volume=68|date=1 April 2010|publisher=Catholic University of America Press|isbn=978-0-8132-1168-8|ref={{harvid|Chrysostom}}}}
* {{citation|author1=Epiphanius of Salamis|author-link1=Epiphanius of Salamis|last2=Williams|first2=Frank (trans)|title=The Panarion of Epiphanius of Salamis|url=https://books.google.com/books?id=DAP-uJTfc84C|year=1994|publisher=Brill|location=Leiden |isbn=90-04-09898-4|ref={{harvid|Panarion}}}}
* {{citation|author=Hilary of Poitiers|author-link=Hilary of Poitiers|title=Contra Constantium Augustum Liber|trans-title=A Book Against the Emperor Constantine|ref={{harvid|Contra Constantium Augustum Liber}}}}
* {{citation|author=Jerome|author-link=Jerome|title=Temporum Liber|trans-title=The Book of Times|ref={{harvid|Temporum Liber}}}}
* {{citation|author1=Photios I of Constantinople|author-link1=Photios I of Constantinople|last2=Walford|first2=Edward (trans)|title=Epitome of the Ecclesiastical History of Philostorgius, Compiled by Photius, Patriarch of Constantinople |url=http://www.tertullian.org/fathers/philostorgius.htm|ref={{harvid|Photius I}}}}

=== Secondary sources ===
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{{Div col end}}

==Further reading==
*{{Cite book |last= |title=Fontes Nicaenae Synodi: The Contemporary Sources for the Study of the Council of Nicaea (304–337) |publisher=[[Brill Publishers]] |year=2024 |isbn=978-3-657-79640-3 |editor-last=Fernández |editor-first=Samuel}}
*{{cite journal |last1=Fernández |first1=Samuel |title=Who convened the First Council of Nicaea: Constantine or Ossius? |journal=The Journal of Theological Studies |date=2020 |volume=71 |pages=196–211 |doi=10.1093/jts/flaa036}}
*[http://www.christianitytoday.com/ch/2005/issue85/theroadtonicaea.html The Road to Nicaea] A descriptive overview of the events of the council, by [[John Anthony McGuckin]].
*{{citation|title=Council of Nicaea|encyclopedia=Encyclopædia Britannica|date=2 January 2024 |url=https://www.britannica.com/EBchecked/topic/413817/Council-of-Nicaea}}

== External links ==
{{Wikiversity|Council of Nicea (325 A.D.)}}
* [http://www.fourthcentury.com/index.php/nicaea-325-canons Canons of the Council of Nicaea], sponsored by [[Wisconsin Lutheran College]] and [https://www.als.org.hk Asia Lutheran Seminary].
* [https://www.fourthcentury.com/council-of-nicaea-ad-325/ Updated English Translations of the Council proceedings, Creed, Rulings (Canons), and Letters Connected to the Council], from the above site.

{{Ecumenical councils|uncollapsed}}
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{{DEFAULTSORT:Council Of Nicaea 1}}
[[Category:4th-century church councils|Nicaea 1]]
[[Category:320s in the Roman Empire]]
[[Category:First seven ecumenical councils|Nicaea 1]]
[[Category:Trinitarianism]]
[[Category:Arianism]]
[[Category:Constantine the Great and Christianity]]
[[Category:Roman Bithynia]]
[[Category:Nicaea]]
[[Category:325]]
[[Category:Date of Easter]]
[[Category:Nature of Jesus Christ]]