Pope Pelagius II, in his epistle “Quod ad dilectionern” (c. 585), confirms the following profession of faith from the Council of Nicea (the first ecumenical council): “We believe in one God the Father omnipotent, maker of the visible and invisible things. And in one Lord Jesus Christ, the Son of God, begotten of the Father, Who [Latin: Hoc] is of the substance of the Father, God of God, Light of Light, True God of True God, begotten not made, of one substance with the Father, whom the Greeks call consubstantial [Latin: “homousion”; Greek for “the same substance as”], through Whom all things are [having been] made [facta sunt] whether those things [were made] in heaven or which [were made] on earth; Who for us men [“homines”] and for our salvation came down, became incarnate, became man, suffered and rose again on the third day, ascended into heaven, is [/will be] coming [Latin “venturus”] to judge the living and the dead. And [we believe] in the Holy Spirit.
“But those who say: ‘there was once when He was not,’ and ‘prior to [priusquam] being begotten, He was not, and He was made from out of non-existence [Latin “ex nullis exantibus” lit. “out of none existing things”] which the Greeks call ‘exuconton’ or [Latin “vel” meaning “or [interchangeably]”] ‘an other substance’ [Greek text says ‘ex heteras hypostaseos e ousias’ or ‘out of another (different) hypostasis or substance’], stating the Son of God [to be] changeable or convertible; these [persons] the Catholic and Apostolic Church anathematizes [declares to be cursed/set apart from on High (by God).]”—The First Council of Nicaea, Profession of Faith of the Council Fathers, 325 AD