Council of Nicea

Definition: Council of Nicea
Council of Christian bishops convened by Emperor Constantine in 325 in modern-day Iznik, Turkey. Condemned Arianism as a heresy and produced the Nicene Creed.

The Council of Nicea was an important meeting of about 300 Christian bishops from across the Roman Empire in 325 CE to discuss theological and administrative issues, including the divinity of Jesus Christ. They met in Nicea, which is located in modern Iznik, Turkey. The Council of Nicea is best known for resulting in the Nicene Creed, which is still used by most Christian denominations today as a statement of faith.

Constantine and Arianism

Emperor Constantine had recently converted to Christianity and hoped his new faith would be the uniting force of his empire. He was thus distressed to hear of the dispute over Arianism.

Named for Arius, a priest in Alexandria, Egypt, Arianism held that Jesus Christ was divine but not quite equal to God. Arians held that Christ did not always exist along with the Father (was not "coeternal"), but was begotten by him before the world and even time itself was created. The two divine beings were of "similar substance" but not the same substance (not "consubstantial").

So in 325, Constantine convened a council of Christian bishops at Nicea (modern Iznik, Turkey) with full confidence that they could work out their differences.

The gathering at Nicea was significant both historically and theologically.

Although many local synods had been held, the Council of Nicea was the first to include bishops from several different regions, and is thus considered the first "ecumenical council" of the church. All three main branches of Christianity - Roman Catholic, Eastern Orthodox, and Protestant - still consider the decisions of this and six other ecumenical councils to be authoritative.

The Council of Nicea also illustrated a dramatic shift in Christianity's status. After centuries of persecution by Roman officials, Christian bishops from across the Empire now journeyed to Nicea under state protection to discuss theological problems with the help of the Roman emperor.

Official persecution had been so recent that many of the bishops still bore its scars; Constantine himself is said to have kissed the eyeless cheek of one attendee.

The Nicene Creed

By overwhelming majority, the bishops at the Council of Nicea voted to reject Arianism and condemn it as a heresy. The Nicene bishops also defined orthodox ("correct") Christian belief, focusing especially on the Son's relationship to the Father and using language specifically designed to refute Arius' teachings.

The official statement of faith issued by the Council of Nicea is called the Nicene Creed, which is still recited in many Christian churches today:

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, the only-begotten of his Father, of the substance of the Father, God of God, Light of Light, very God of very God, begotten, not made, being of one substance (homousion) with the Father, by whom all things were made, both which be in heaven and in earth, who for us men and for our salvation came down and was incarnate and was made man. He suffered and the third day he rose again, and ascended into heaven. And he shall come again to judge both the quick and the dead. And [we believe] in the Holy Ghost. And whosoever shall say that there was a time when the Son of God was not, or that before he was begotten he was not, or that he was made of things that were not, or that he is of a different substance or essence [from the Father] or that he is a creature, or subject to change or conversion—all that so say, the Catholic and Apostolic Church anathematizes them.

In addition to the creed, the bishops at the Council of Nicea issued 20 canons, or determinations, after the conclusion of the council. Most of them are fairly mundane and deal with administrative matters.

Primary Sources on the Council of Nicea

As the Council of Nicea was of such importance to the early church, quite a bit of information survives in ancient documents. Several church historians who lived during or shortly after the Council of Nicea documented the events of the council. In addition, writers such as Athanasius (the main defender of Nicene orthodoxy) referred to it in their letters.

  • Eusebius, Life of Constantine 3.4-23 (eyewitness account of a bishop at the council)
  • Athanasius, Letter to Bishops of Africa (eyewitness account)
  • Athanasius, Defense of the Nicene Definition (eyewitness, mainly on theology)
  • Theodoret, Ecclesiastical History 1.7 (early 400s)
  • Socrates Scholasticus, Ecclesiastical History 1.7-9 (early 400s)
  • Sozomen, Ecclesiastical History 1.15-17 (early 400s)

This Nicene Creed is documented in several contemporary sources, including the Acts of the Ecumenical Councils of Ephesus and Acts of Chalcedon, in the Epistle of Eusebius of Cæsarea to his own church, in the Ecclesiastical Histories of Theodoret and Socrates, and elsewhere.


  • "Christianity." Encyclopædia Britannica (Encyclopædia Britannica Premium Service, 2004).
  • Justo Gonzalez, A History of Christian Thought, Vol 1.
  • Kenneth Scott Latourette, A History of Christianity, Vol 1.
  • Philip Schaff, ed., "The Canons of the 318 Holy Fathers Assembled in the City of Nicea" in Nicene and Post Nicene Fathers, Series 2
  • Christian History & Biography Issue 85: Debating Jesus' Divinity - on the Council of Nicea

Article Info

Title Council of Nicea
Last UpdatedFebruary 13, 2021
MLA Citation “Council of Nicea.” 13 Feb. 2021. Web. Accessed 17 Oct. 2021. <>