The very fact that Constantine called the Bishops of the Church to meet at this time indicates how seriously he viewed the necessity of the Council. The Council issued its Creed, that is known today as the Nicene Creed. We believe . This formula of the Council of Nice became the standard formula for the future of the Church. In 381, the Second Ecumenical Council of the Church, known as the First Council of Constantinople, declared its Creed in words almost identical with those of the Council of Nice.
Truth is one, yet there are many ways of falsifying or of denying it.
If the day is sunny, there is only one way of saying the truth about the sunny day. After Arius came Nestorius, the patriarch of Constantinople, who began in the year 428 to assert that the Blessed Mother was not the Mother of God. He said that he would never accept as God an infant of two months, and that it was not God Who died, but man. Nestorius would not admit that there is but one person in Christ, the divine person of the Word. Instead he said that there were two persons, the divine person, and the human person of whom Mary was the Mother.