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Council of Nicaea and the Nicene Creed
AD 325· Event· Judaism, Christianity & Islam
Historical recordConfirmed by archaeology, outside sources or contemporary records.
The first empire-wide council of Christian bishops, called by Constantine in AD 325 to settle whether Christ was fully God.
See it on the World Religions map →What it is
Arius, a priest of Alexandria, taught that the Son was created by the Father and so was not eternal. The dispute split churches across the East. Constantine summoned bishops, traditionally 318, to Nicaea (today İznik, Turkey). They condemned Arius and adopted a creed declaring the Son 'of one substance' (homoousios) with the Father. They also set a common way to date Easter. An expanded version of 381, the Nicene Creed, is still recited by Catholic, Orthodox and many Protestant churches.
Why it matters
It set the pattern of councils defining Christian doctrine and shaped belief in the Trinity. Its creed is the most widely shared Christian statement of faith; 2025 marked its 1,700th anniversary.
Sources and history
The creed and canons survive; accounts by attendees Eusebius of Caesarea and Athanasius; letters of Constantine. No official minutes survive, if any were kept.
Questions and debates
A popular myth says Nicaea chose the Bible's books; it did not. Historians debate how much Constantine shaped the outcome; Arian views persisted for decades.
Connections (4)
▸Council of Nicaea and the Nicene Creed affirmed Christ's divinity within Monotheism: belief in one GodHistorical record
The connection
Christians inherited Judaism's insistence on one God but also worshipped Jesus. Arius eased the tension by making the Son a lesser, created being. Nicaea instead declared the Son 'of one substance' with the Father: one God, not two. This opened the way to the doctrine of the Trinity, one God in three persons, defined more fully in 381.
When and where
Nicaea, in Asia Minor, AD 325; Bishop Alexander of Alexandria and his deacon Athanasius led opposition to Arius. The Council of Constantinople in 381 extended the creed to the Holy Spirit.
Historical evidence
The creed's text survives, opening 'We believe in one God'; contemporary letters and church histories record the debate and its outcome.
Questions and debates
Jews and Muslims hold that the Trinity compromises strict monotheism; Christians maintain it is monotheism. Unitarians and some other groups also reject it.
▸Constantine, the first Christian emperor convened Council of Nicaea and the Nicene CreedHistorical record
The connection
The Arian dispute was splitting the church just as Constantine reunited the empire in 324. Wanting one church to match one empire, he summoned bishops to Nicaea, paid their travel, opened the council in person and urged agreement. He then exiled Arius and the bishops who would not sign, enforcing the result with imperial power.
When and where
Nicaea (İznik, Turkey), near his residence at Nicomedia, summer AD 325, with roughly 250–300 bishops, mostly from the East.
Historical evidence
Eusebius of Caesarea, who attended, describes Constantine's role; Constantine's own letters about the council survive.
Questions and debates
How far Constantine pushed the key term homoousios himself is debated; he later readmitted Arius and was baptized by an Arian-leaning bishop.
▸Council of Nicaea and the Nicene Creed shaped the creeds of Eastern Orthodox ChurchHistorical record
The connection
The Council of Nicaea (325) defined the Son as 'of one substance' with the Father, and its creed, expanded at Constantinople in 381, is recited at every Orthodox Divine Liturgy. The Orthodox treat Nicaea as the first of seven ecumenical councils that define true faith, and reject the West's later addition of filioque to the creed.
When and where
Nicaea (modern İznik, Turkey), 325, called by Constantine; about 250–318 bishops attended, mostly from the Greek-speaking East.
Historical evidence
The creed's text, the council's canons, and accounts by Eusebius and Athanasius, who attended; Orthodox service books still use the creed.
Questions and debates
Scholars debate whether the expanded creed really came from the 381 council, since it is first recorded only in 451; the filioque dispute remains unresolved.
▸Jehovah's Witnesses rejects the creed of Council of Nicaea and the Nicene CreedHistorical record
The connection
The Nicene Creed (325) declared the Son 'of one substance' with the Father, a cornerstone of Trinitarian belief. Jehovah's Witnesses reject it, teaching that Jehovah alone is almighty God and that Jesus is God's first creation and son, not his equal. They see the creed as a later departure from the Bible.
When and where
Russell taught this from the 1870s in Pittsburgh; Witness literature such as 'Should You Believe in the Trinity?' (1989) sets out the case.
Historical evidence
Witness publications and their New World Translation of the Bible (1950–61) reflect the view, for example rendering John 1:1 as 'the Word was a god'.
Questions and debates
Scholars debate how closely Witness teaching matches ancient Arianism, the view the council condemned; Witnesses say they follow scripture, not Arius.