The rule of truth requires that we should first of all things believe on God the Father and Lord Almighty (I).
And over all these things He Himself, containing all things, having nothing vacant beyond Himself, has left room for no superior God, such as some people conceive. (II).
The same rule of truth teaches us to believe, after the Father, also on the Son of God, Christ Jesus, the Lord our God, but the Son of God--of that God who is both one and alone, to wit the Founder of all things, as already has been expressed above. (IX).
But lest, from the fact of asserting that our Lord Jesus Christ, the Son of God, the Creator, was manifested in the substance of the true body, we should seem either to have given assent to other heretics, who in this place maintain that He is man only and alone, and therefore desire to prove that He was a man bare and solitary; and lest we should seem to have afforded them any ground for objecting, we do not so express doctrine concerning the substance of His body, as to say that He is only and alone man, but so as to maintain, by the association of the divinity of the Word in that very materiality, that He was also God according to the Scriptures. For there is a great risk of saying that the Saviour of the human race was only man; that the Lord of all, and the Chief of the world, to whom all things were delivered, and all things were granted by His Father, by whom all things were ordained, all things were created, all things were arranged, the King of all ages and times, the Prince of all the angels, before whom there is none but the Father, was only man, and denying to Him divine authority in these things.... For Scripture as much announces Christ as also God, as it announces God Himself as man. It has as much described Jesus Christ to be man, as moreover it has also described Christ the Lord to be God. Because it does not set forth Him to be the Son of God only, but also the Son of man; nor does it only say, the Son of man, but it has also been accustomed to speak of Him as the Son of God. So that being of both, He is both, lest if He should be one only, He could not be the other. For as nature itself has prescribed that he must be believed to be a man who is of man, so the same nature prescribes also that He must be believed to be God who is of God; but if he should not also be God when be is of God, no more should he be man although he should be of man. And thus both doctrines would be endangered in one and the other way, by one being convicted to have lost belief in the other. Let them, therefore, who read that Jesus Christ the Son of man is man, read also that this same Jesus is called also God and the Son of God. For in the manner that as man He is of Abraham, so also as God He is before Abraham himself. And in the same manner as He is as man the Son of David, so as God He is proclaimed David's Lord. And in the same manner as He was made as man under the law, Galatians 4:4 so as God He is declared to be Lord of the Sabbath. And in the same manner as He suffers, as man, the condemnation, so as God He is found to have all judgment of the quick and dead. And in the same manner as He is born as man subsequent to the world, so as God He is manifested to have been before the world. And in the same way as He was begotten as man of the seed of David, so also the world is said to have been ordained by Him as God. And in the same way as He was as man after many, so as God He was before all. And in the same manner as He was as man inferior to others, so as God He was greater than all. And in the same manner as He ascended as man into heaven, so as God He had first descended thence. And in the same manner as He goes as man to the Father, so as the Son in obedience to the Father He shall descend thence. So if imperfections in Him prove human frailty, majesties in Him affirm divine power. For the risk is, in reading of both, to believe not both, but one of the two. Wherefore as both are read of in Christ, let both be believed; that so finally the faith may be true, being also complete. For if of two principles one gives way in the faith, and the other, and that indeed which is of least importance, be taken up for belief, the rule of truth is thrown into confusion; and that boldness will not confer salvation, but instead of salvation will effect a great risk of death from the overthrow of the faith.
Why, then, should we hesitate to say what Scripture does not shrink from declaring? Why shall the truth of faith hesitate in that wherein the authority of Scripture has never hesitated? For, behold, Hosea the prophet says in the person of the Father: I will not now save them by bow, nor by horses, nor by horsemen; but I will save them by the Lord their God. Hosea 1:7 If God says that He saves by God, still God does not save except by Christ. Why, then, should man hesitate to call Christ God, when he observes that He is declared to be God by the Father according to the Scriptures? Yea, if God the Father does not save except by God, no one can be saved by God the Father unless he shall have confessed Christ to be God, in whom and by whom the Father promises that He will give him salvation: so that, reasonably, whoever acknowledges Him to be God, may find salvation in Christ God; whoever does not acknowledge Him to be God, would lose salvation which he could not find elsewhere than in Christ God. For in the same way as Isaiah says, Behold, a virgin shall conceive and bear a son, and you shall call His name Emmanuel, which is, interpreted, God with us. so Christ Himself says, Lo, I am with you, even to the consummation of the world. Matthew 28:20 Therefore He is God with us; yea, and much rather, He is in us. Christ is with us, therefore it is He whose name is God with us, because He also is with us; or is He not with us? How then does He say that He is with us? He, then, is with us. But because He is with us He was called Emmanuel, that is, God with us. God, therefore, because He is with us, was called God with us.... What, then, do they reply when those signs are said to be about to take place on the advent of God, which were manifested on the advent of Christ? In what way do they receive Christ as God? For now they cannot deny Him to be God. As God the Father, or as God the Son? If as the Son, why do they deny that the Son of God is God? If as the Father, why do they not follow those who appear to maintain blasphemies of that kind? Unless because in this contest against them concerning the truth, this is in the meantime sufficient for us, that, being convinced in any kind of way, they should confess Christ to be God, seeing they have even wished to deny that He is God. He says by Habakkuk the prophet: God shall come from the south, and the Holy One from the dark and dense mountain. Whom do they wish to represent as coming from the south? If they say that it is the Almighty God the Father, then God the Father comes from a place, from which place, moreover, He is thus excluded, and He is bounded within the straitnesses of some abode; and thus by such as these, as we have said, the sacrilegious heresy of Sabellius is embodied. Since Christ is believed to be not the Son, but the Father; since by them He is asserted to be in strictness a bare man, in a new manner, by those, again, Christ is proved to be God the Father Almighty. But if in Bethlehem, the region of which local division looks towards the southern portion of heaven, Christ is born, who by the Scriptures is also said to be God, this God is rightly described as coming from the south, because He was foreseen as about to come from Bethlehem. Let them, then, choose of the two alternatives, the one that they prefer, that He who came from the south is the Son, or the Father; for God is said to be about to come from the south. If the Son, why do they shrink from calling Him Christ and God? For the Scripture says that God shall come. If the Father, why do they shrink from being associated with the boldness of Sabellius, who says that Christ is the Father? Unless because, whether they call Him Father or Son, from his heresy, however unwillingly, they must needs withdraw if they are accustomed to say that Christ is merely man; when compelled by the facts themselves, they are on the eve of exalting Him as God, whether in wishing to call Him Father or in wishing to call Him Son.(XII).
And thus also John, describing the nativity of Christ, says: The Word was made flesh, and dwelt among us, and we saw His glory, the glory as of the only begotten of the Father, full Of grace and truth.. For, moreover, His name is called the Word of God... For the world was made by Him, and the world knew Him not. John 1:10-11 Moreover, this Word was in the beginning with God, and God was the Word. John 1:1 Who then can doubt, when in the last clause it is said, The Word was made flesh, and dwelt among us, that Christ, whose is the nativity, and because He was made flesh, is man; and because He is the Word of God, who can shrink from declaring without hesitation that He is God, especially when he considers the evangelical Scripture, that it has associated both of these substantial natures into one concord of the nativity of Christ?....whereas it is the portion of no man to come from heaven, He descended by coming from heaven; and if, whereas this word can be true of no man, I and the Father are one, John 10:30 Christ alone declared this word out of the consciousness of His divinity; and if, finally, the Apostle Thomas, instructed in all the proofs and conditions of Christ's divinity, says in reply to Christ, My Lord and my God; John 20:28 and if, besides, the Apostle Paul says, Whose are the fathers, and of whom Christ came according to the flesh, who is over all, God blessed for evermore. writing in his epistles; and if the same apostle declares that he was ordained an apostle not by men, nor of man, but by Jesus Christ; and if the same contends that he learned the Gospel not from men or by man, but received it from Jesus Christ, reasonably Christ is God. Therefore, in this respect, one of two things must needs be established. For since it is evident that all things were made by Christ, He is either before all things, since all things were by Him, and so He is justly God; or because He is man He is subsequent to all things, and justly nothing was made by Him. But we cannot say that nothing was made by Him, when we observe it written that all things were made by Him. He is not therefore subsequent to all things; that is, He is not man only, who is subsequent to all things, but God also, since God is prior to all things. For He is before all things, because all things are by Him, while if He were only man, nothing would be by Him; or if all things were by Him, He would not be man only, because if He were only man, all things would not be by Him; nay, nothing would be by Him. What, then, do they reply? That nothing is by Him, so that He is man only? How then are all things by Him? Therefore He is not man only, but God also, since all things are by Him; so that we reasonably ought to understand that Christ is not man only, who is subsequent to all things, but God also, since by Him all things were made. For how can you say that He is man only, when you see Him also in the flesh, unless because when both aspects are considered, both truths are rightly believed?
And yet the heretic still shrinks from urging that Christ is God, whom he perceives to be proved God by so many words as well as facts. If Christ is only man, how, when He came into this world, did He come unto His own, since a man could have made no world? If Christ was only man, how is the world said to have been made by Him, when the world was not by man, but man was ordained after the world? If Christ was only man, how was it that Christ was not only of the seed of David; but He was the Word made flesh and dwelt among us? For although the Protoplast was not born of seed, yet neither was the Protoplast formed of the conjunction of the Word and the flesh. For He is not the Word made flesh, nor dwelt in us. If Christ was only man, how does He who comes from heaven testify what He has seen and heard, John 3:31 when it is plain that man cannot come from heaven, because he cannot be born there? If Christ be only man, how are visible things and invisible, thrones, powers, and dominions, said to be created by Him and in Him; when the heavenly powers could not have been made by man, since they must needs have been prior to man? If Christ is only man, how is He present wherever He is called upon; when it is not the nature of man, but of God, that it can be present in every place? If Christ is only man, why is a man invoked in prayers as a Mediator, when the invocation of a man to afford salvation is condemned as ineffectual? If Christ is only man, why is hope rested upon Him, when hope in man is declared to be accursed? If Christ is only man, why may not Christ be denied without destruction of the soul, when it is said that a sin committed against man may be forgiven? If Christ is only man, how comes John the Baptist to testify and say, He who comes after me has become before me, because He was prior to me; John 1:15 when, if Christ were only man, being born after John, He could not be before John, unless because He preceded him, in that He is God? If Christ is only man, how is it that what things the Father does, these also does the Son likewise, John 5:19 when man cannot do works like to the heavenly operations of God? If Christ is only man, how is it that even as the Father has life in Himself, so has He given to the Son to have life in Himself, John 5:26 when man cannot have life in him after the example of God the Father, because he is not glorious in eternity, but made with the materials of mortality? If Christ is only man, how does He say, I am the bread of eternal life which came down from heaven, John 6:51 when man can neither be the bread of life, he himself being mortal, nor could he have come down from heaven, since no perishable material is established in heaven? If Christ is only man, how does He say that no man has seen God at any time, save He which is of God; He has seen God? Because if Christ is only man, He could not see God, because no man has seen God; but if, being of God, He has seen God, He wishes it to be understood that He is more than man, in that He has seen God. If Christ is only man, why does He say, What if you shall see the Son of man ascending there where He was before? But He ascended into heaven, therefore He was there, in that He returned there where He was before. But if He was sent from heaven by the Father, He certainly is not man only; for man, as we have said, could not come from heaven. Therefore as man He was not there before, but ascended there where He was not. But the Word of God descended which was there—the Word of God, I say, and God by whom all things were made, and without whom nothing was made. It was not therefore man that thus came thence from heaven, but the Word of God; that is, God descended thence. (XIV).
Thus God the Father, the Founder and Creator of all things, who only knows no beginning, invisible, infinite, immortal, eternal, is one God; to whose greatness, or majesty, or power, I would not say nothing can be preferred, but nothing can be compared; of whom, when He willed it, the Son, the Word, was born. (XXXI).
Thus the Mediator of God and men, Christ Jesus, having the power of every creature subjected to Him by His own Father, inasmuch as He is God; with every creature subdued to Him, found at one with His Father God, has, by abiding in that condition that He moreover "was heard," briefly proved God His Father to be one and only and true God. (XXXI).