Isa 43:11

“If you want to have me as a witness to your verdict, then be the first to render witness to my truth. In this case, I will not be alone in bearing witness, but there is also my chosen servant. Now it is neither Moses nor another of the prophets who is referred to here, but Christ our Master. And he calls him a [servant], not as God but as a human being; for it is as a human being that he has named him "chosen." … We likewise find in the holy Gospels this number of two witnesses. In the course of a conversation with the Jews our Master Christ in effect declared, "It is written in your law that the testimony of two persons is true. I bear witness concerning myself, and the Father who sent me bears witness." … "I am, I am your God, and there is no other savior besides me." Again these words proclaim the one divinity. For our Master Christ is called "savior" throughout the holy Scriptures, as I think even the followers of Arius and Eunomius would concede. Now if apart from God there is no savior and if Christ is called "Savior," it is clear that he participates in the [divine] nature. If Christ does not, as the blasphemers allege, then he is not Savior.… But if he is Savior, then he shares the same essence to which alone belongs the faculty of saving.”

“It has been sufficiently demonstrated that God exists and that his essence is incomprehensible. Furthermore, those who believe in sacred Scripture have no doubt that he is one and not several. For the Lord says at the beginning of his lawgiving, "I am the Lord your God, who brought you out of the land of Egypt. You shall not have strange gods before me." And again: "Hear, O Israel: the Lord your God is one Lord." And through the mouth of the prophet Isaiah: "I am," he says, "the first God, and I am the last, and there is no God besides me. Before me there was no God, and after me there shall be none, and beside me there is none." And the Lord speaks thus to his Father in the holy Gospels: "This is eternal life: that they may know you, the only true God." With those who do not believe in sacred Scripture we shall reason as follows. The Divinity is perfect and without deficiency in goodness or wisdom or power. He is without beginning, without end, eternal, uncircumscribed; to put it simply, he is perfect in all things. Now, if we say that there are several gods, there must be some difference to be found among them. For if there is no difference at all among them, then there is one God rather than several. But if there is some difference, then where is the perfection? For if one should come short of perfection in goodness, or power, or wisdom, or time or place, then he would not be God. The identity of God in all things shows him to be one and not several.”

“I, I. The word is repeated, as if to say, I do not change as the host of heaven does with regard to its centre, nor as earthly things do with regard to substance and form; I can therefore help at every time.”

“And that he alone is Lord: I am, singularly, I am, preeminently: neither is there salvation in any other (Acts 4:12).”