Isaias 44:6

The prophets also, when they speak as in the person of God, [saying,] “I am God, the first [of beings], and I am also the last, and besides Me there is no God,” concerning the Father of the universe, do also speak of our Lord Jesus Christ. “A Son,” they say, has been given to us, on whose shoulder the government is from above; and His name is called the Angel of great counsel, Wonderful, Counsellor, the strong and mighty God.” And concerning His incarnation, “Behold, a virgin shall be with Child, and shall bring forth a Son; and they shall call his name Immanuel.” And concerning the passion, “He was led as a sheep to the slaughter; and as a lamb before her shearers is dumb, I also was an innocent lamb led to be sacrificed.”

For God cannot be called by any proper name, for names are given to mark out and distinguish their subject-matters, because these are many and diverse; but neither did any one exist before God who could give Him a name, nor did He Himself think it right to name Himself, seeing that He is one and unique, as He Himself also by His own prophets testifies, when He says, “I God am the first,” and after this, “And beside me there is no other God.” On this account, then, as I before said, God did not, when He sent Moses to the Hebrews, mention any name, but by a participle He mystically teaches them that He is the one and only God. “For,” says He; “I am the Beingi ;” manifestly contrasting Himself, “the Being,” with those who are not, that those who had hitherto been deceived might see that they were attaching themselves, not to beings, but to those who had no being. …

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 …

He declares that God’s attribute is still safe to Him, of being the only God, and the First, and the Author of all things, and the Lord of all things, and being incomparable to any, qualities which he straightway ascribes to Matter also. He is God, to be sure. God shall also attest the same; but He has also sworn sometimes by Himself, that there is no other God like Him. Hermogenes, however, will make Him a liar. For Matter will be such a God as He, being unmade, unborn, without beginning, and without end. God will say, “I am the first!” Yet how is He the first, when Matter is co-eternal with Him? Between co-eternals and contemporaries there is no sequence of rank. Is then, Matter also the first? “I,” says the Lord, “have stretched out the heavens alone.” But indeed He was not alone, when that likewise stretched them out, of which He made the expanse. …

But what hinders them from readily perceiving this community of the Father’s titles in the Son, is the statement of Scripture, whenever it determines God to be but One; as if the selfsame Scripture had not also set forth Two both as God and Lord, as we have shown above. Their argument is: Since we find Two and One, therefore Both are One and the Same, both Father and Son. Now the Scripture is not in danger of requiring the aid of any one’s argument, lest it should seem to be self-contradictory. It has a method of its own, both when it sets forth one only God, and also when it shows that there are Two, Father and Son; and is consistent with itself. It is clear that the Son is mentioned by it. …

2. Now they seek to exhibit the foundation for their dogma by citing the word in the law, “I am the God of your fathers: ye shall have no other gods beside me;” and again in another passage, “I am the first,” He saith, “and the last; and beside me there is none other.” Thus they say they prove that God is one. And then they answer in this manner: “If therefore I acknowledge Christ to be God, He is the Father Himself, if He is indeed God; and Christ suffered, being Himself God; and consequently the Father suffered, for He was the Father Himself.” But the case stands not thus; for the Scriptures do not set forth the matter in this manner. But they make use also of other testimonies, and say, Thus it is written: “This is our God, and there shall none other be accounted of in comparison of Him. …

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; …

We may use an example more closely connected with us. When any one has a son whom he especially loves, who is still in the house, and in the power of his father, although he concede to him the name and power of a master, yet by the civil law the house is one, and one person is called master. So this world is the one house of God; and the Son and the Father, who unanimously inhabit the world, are one God, for the one is as two, and the two are as one. Nor is that wonderful, since the Son is in the Father, for the Father loves the Son, and the Father is in the Son; for He faithfully obeys the will of the Father, nor does He ever do nor has done anything except what the Father either willed or commanded. …

Finally, how could the expression, “All things were made by Him,” be true? For if there is an age older than He, how can that which was before Him have been made by Him? See ye to what daring the argument has carried them, when once the truth has been unsettled? Why did not the Evangelist say, that He was made from things that were not, as Paul declares of all things, when he says, “Who calleth those things which be not as though they were”; but says, “Was in the beginning”? ( Rom. iv. 17 .) This is contrary to that; and with good reason. For God neither is made, nor has anything older; these are words of the Greeks. …

‘We believe in one God the Father Almighty, the Creator and Maker of all things, of whom the whole family in heaven and on earth is named, and in his only begotten Son, our Lord Jesus Christ, who was begotten of the Father before all ages, God of God, Light of Light, by whom all things visible and invisible, which are in the heavens and upon the earth, were made: who is the Word, and the Wisdom, and the true Light, and the Life; who in the last days for our sake was made man and born of the holy virgin, and was crucified and died, and was buried, and rose again from the dead on the third day, and was received up into heaven, and sat at the right hand of the Father, and is coming at the completion of the age to judge the living and the dead, and to requite every one according to his works: whose kingdom being everlasting, endures into infinite ages; for he will be seated at the Father’s r …

6. And this is what is said, ‘Who being in the form of God,’ and ‘the Father in Me.’ Nor is this Form of the Godhead partial merely, but the fulness of the Father’s Godhead is the Being of the Son, and the Son is whole God. Therefore also, being equal to God, He ‘thought it not a prize to be equal to God;’ and again since the Godhead and the Form of the Son is none other’s than the Father’s, this is what He says, ‘I in the Father.’ Thus ‘God was in Christ reconciling the world unto Himself;’ for the propriety of the Father’s Essence is that Son, in whom the creation was then reconciled with God. Thus what things the Son then wrought are the Father’s works, for the Son is the Form of that Godhead of the Father, which wrought the works. …

(11.) Whosoever shall explain ‘I God the First and I the Last, and besides Me there is no God,’ ( Is. xliv. 6 ), which is said for the denial of idols and of gods that are not, to the denial of the Only-begotten, before ages God, as Jews do, be he anathema.