The Council of Nicaea (325)
The Nicene Creed
This creed is found in the Acts of the ecumenical councils of Ephesus and Chalcedon, in the letter Eusebius of Caesarea wrote to his own church, in Saint Athanasius’s letter to the emperor Jovian, in the church histories of Theodoret and Socrates, and elsewhere. The differences between the copies are of no importance at all. The synod at Nicaea set forth this creed. The statement of faith of the synod at Nicaea.
But as for those who 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 out 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 alteration: all who say such things, the catholic and apostolic church anathematizes.