The early church, by which is meant circa 100AD to 300AD was characterised by debate. The subjects revolved around the true meaning of God and Jesus together with trying to determine the exact nature of Jesus. The Church itself was established and had a command heirachy of bishops and clergy. Some bishops and clergy holding to one theory of divinity with others holding a divergent view. Some of the arguments were fundamental to the beliefs of Christianity such as whether Jesus was the Son of God and therefore eternal, whilst others argued that as a son he must have been fathered by God and therefore had a beginning i.e. a birth even before his appearance on earth.

The debate on this and other subjects threatened the unity and cohesiveness of the Church and the five senior bishops, lead by Constantine, called a conference in the city of Nicaea to try and settle the matter. The conference convened on the 19 June 325. One of the matters it settled was the date of Easter, or perhaps more accurately, the manner of calculating the date of Easter Sunday. It was at this conference that it was decided that Easter would be on a Sunday. From the Anglican perspective the major decision of the conference was the adoption of the concept of the Holy Trinity, Father, Son and Holy Ghost, the three in one, thereby rejecting the theory that the Son was a created being.

The doctrine of the Council was encapsulated in a Creed, which came to be called the Nicene Creed, and with slightly updated wording (some alterations arising from further conferences over many hundreds of years), still today, forms the central belief of the Anglican Communion, of which the Church of England is a part. It is recited in the main service of the church, the Eucharist or Communion service and in some other services also. It is reproduced below in its "traditional" form, from the Book of Common Prayer (1662) and in its modern form introduced in 2000.

1662 Book of Common Prayer

I believe in one God the Father Almighty, Maker of heaven and earth, And of all things visible and invisible: And in one Lord Jesus Christ, the only-begotten Son of God, Begotten of his Father before all worlds, 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; Who for us men, and for our salvation came down from heaven, And was incarnate by the Holy Ghost of the Virgin Mary, And was made man, And was crucified also for us under Pontius Pilate. He suffered and was buried, And the third day he rose again according to the Scriptures, And ascended into heaven, And sitteth on the right hand of the Father. And he shall come again with glory to judge both the quick and the dead: Whose kingdom shall have no end. And I believe in the Holy Ghost, The Lord and giver of life, Who proceedeth from the Father and the Son, Who with the Father and the Son together is worshipped and glorified, Who spake by the Prophets. And I believe one Catholick and Apostolick Church. I acknowledge one Baptism for the remission of sins. And I look for the Resurrection of the dead, And the life of the world to come. Amen

Church of England Common Worship version (2000)

We believe in one God, the Father, the Almighty, maker of heaven and earth, of all that is, seen and unseen. We believe in one Lord, Jesus Christ, the only Son of God, eternally begotten of the Father, God from God, Light from Light, true God from true God, begotten, not made, of one Being with the Father; through him all things were made. For us and for our salvation he came down from heaven, was incarnate of the Holy Spirit and the Virgin Mary and was made man. For our sake he was crucified under Pontius Pilate; he suffered death and was buried. On the third day he rose again in accordance with the Scriptures; he ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead, and his kingdom will have no end. We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son, who with the Father and the Son is worshipped and glorified, who has spoken through the prophets. We believe in one holy catholic and apostolic Church. We acknowledge one baptism for the forgiveness of sins. We look for the resurrection of the dead, and the life of the world to come. Amen

COMMENT ; Part of the early debate revolved around whether The Son could have been created by God as if the Son is Eternal there is no creation, having always existed. This lead to dicussions as to whether God could create Himself. It is interesting that one of the advanced theories regarding the creation of the universe in which we live, our physical universe, is that the universe came out of nothing and 'thought' itself into existance. Look up "String Theory" in your favourite search engine. Different format, essentially same debate!