Council of Nicaea

The First Council of Nicaea was a meeting of Christian church leaders held in 325 CE to address issues of theology and clerical law.

It was the first of many such ecumenical councils, and is generally considered the most influential. The Council's rulings about the nature of Jesus Christ, as encapsulated in the "Nicene Creed," established a blueprint for mainstream Christianity which has continued through the Orthodox, Catholic, Protestant, and Anglican traditions throughout most of Christianity's history.

Background
The Council was summoned by Emperor Constantine I, who had converted to Christianity around 312 CE, and had begun to establish Christianity as the state religion of the Roman Empire. Although it would be several decades before it was officially recognised as such, the Emperor wanted to end the factionalism associated with pre-Nicene Christianity and establish a general and uniform set of teachings. He had also begun to develop the city of Nova Roma, later known as Constantinople, formerly Byzantium, and now Istanbul, which was completed in 330 and would later become the seat of the Eastern Empire.

The Council took place in the lakeside city of Nicaea (now Iznik, in modern day Turkey) and lasted over two months. Accounts of the attendees vary, but indicate that approximately three hundred bishops attended, almost of all them from the Eastern half of the Empire. Most prominent were the Patriarchs (Archbishops) of Alexandria, Antioch and Jerusalem. The Bishop of Rome (forerunner to the role of Pope) attended but, contrary to what the Roman Catholic tradition suggests, does not appear to have been among the highest or most influential church leaders. Constantine himself was present, but there is no indication that he took a leading role in the discussion or conclusions.

Arian controversy
Theologically, the greatest reason for the Council was the controversy over Arianism, a belief promoted by the theologian Arius that Jesus, as Son of God, was one of God's creations and hence subordinate to God the Father and Creator. This stood in opposition to the more conventional view, championed by Archbishop Alexander of Alexandria and others, that both God the Father and Christ the Son were of the same substance and hence Jesus was "begotten" rather than created.

Arius was not present at the Council, but some bishops argued in favour of Arianism. Ultimately, however, it was denounced as heresy and the Council affirmed the orthodox view, that God the Father, Christ the Son, and the Holy Ghost were of parts three but equal, a view known as Trinitarianism.

Nicene Creed
The Council's rulings on Christian theology, and especially the response to the Arian controversy, were summarised in an official declaration, known as the Nicene Creed.

The original version of the Creed was as follows:

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 of the Father, the only-begotten; that is, of the essence of the Father, God of God, Light of Light, very God of very God, begotten, not made, being of one substance with the Father; By whom all things were made both in heaven and on 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, ascended into heaven; From thence he shall come to judge the quick and the dead. And in the Holy Ghost.

But those who say: 'There was a time when he was not;' and 'He was not before he was made;' and 'He was made out of nothing,' or 'He is of another substance' or 'essence,' or 'The Son of God is created,' or 'changeable,' or 'alterable' -— they are condemned by the holy catholic and apostolic Church.

The text of the Nicene Creed was revised and elaborated in later years, especially at the Councils of Constantinople in 359 and 381 CE, and the explicitly Arian-bashing final passage was removed. Variants of the Nicene Creed continue to be used in Christian worship among many denominations.

Although the Holy Trinity concept was not emphasised at the Council of Nicaea, the theology of the Nicene Creed effectively condemned the other viewpoints, and the Trinity later became a central concept in Christianity.

Other items on the agenda
The Council of Nicaea also enacted a series of canon laws. These included some issues of hierarchy (such as the authority of the Patriarchs of Alexandria, Antioch and Rome), some of church procedures (such as the proper ordination of bishops), and some laws on Christian practices (such as a prohibition on self-castration and a ban on usury by clergymen).

A dispute over the calculation of Easter was settled, in favour of a system (which wasn't completely finalised until centuries afterwards) based on lunar cycles and the Roman calendar, rather than being tied to the Jewish calendar as some Christians had previously supported (since the crucifixion was believed to have taken place during Passover).

Not on the agenda
Contrary to a recent myth (largely promoted by The Da Vinci Code), the Council of Nicaea was not an editorial committee charged with compiling the Christian Bible from the many scriptures and apocrypha in circulation. Although the Biblical canon underwent changes in the early years of Christianity, it was largely complete by the fifth century CE, evidenced by the issuing of the Vulgate Bible in Latin by Saint Jerome. The most complete lists of New Testament books date from later in the century, which may be a reason for the assumption that they had been decided by one of the ecumenical councils, but there is no reliable evidence that this issue was discussed at Nicaea.