Isaias 43:11

If we satisfied ourselves with advancing such considerations as these, our doctrines might by some be looked upon as human. But, since the voices of the prophets confirm our arguments, for I think that you also, with your great zeal for knowledge, and your great attainments in learning, cannot be ignorant of the writings either of Moses or of Isaiah and Jeremiah, and the other prophets, who, lifted in ecstasy above the natural operations of their minds by the impulses of the Divine Spirit, uttered the things with which they were inspired, the Spirit making use of them as a flute-player breathes into a flute; what, then, do these men say? “The Lord is our God; no other can be compared with Him.” And again: “I am God, the first and the last, and besides Me there is no God.” In like manner: “Before Me there was no other God, and after Me there shall be none; I am God, and there is none besi …

And now, indeed, concerning the Father, and the Son, and the Holy Spirit, let it be sufficient to have briefly said thus much, and to have laid down these points concisely, without carrying them out in a lengthened argument. For they could be presented more diffusely and continued in a more expanded disputation, since the whole of the Old and New Testaments might be adduced in testimony that thus the true faith stands. But because heretics, ever struggling against the truth, are accustomed to prolong the controversy of pure tradition and Catholic faith, being offended against Christ; because He is, moreover, asserted to be God by the Scriptures also, and this is believed to be so by us; we must rightly, that every heretical calumny may be removed from our faith, contend, concerning the fact that Christ is God also, in such a way as that it may not militate against the truth of Scripture; …