How in virtue of the hypostatic union of the two natures in Christ the Word is rightly termed the Saviour, or incarnate man, and the Son of God.
And so it is clear that through the mystery of the Word of God joined to man, the Word, which was sent to save men, can be termed Saviour, and the Saviour, who was born in the flesh, can through union with the Word be called the Son of God; and so through the indifferent use of either title, since God is joined to man, whatever is God and man, can be termed altogether God. 2456 And so the same Apostle well adds the words: “Whoever believeth that Jesus is the Son of God, God abideth in him, and the love of God is perfected in him.” 2457 He tells us that he believes, and declares that he is filled with divine love, who believes that Jesus is the Son of God. But he testifies that the Word of God is the Son of God, and thus means us fully to understand that the only begotten Word of God, and Jesus Christ the Son of God are one and the same Person. But do you want to be told more fully that,—though Christ according to the flesh was truly born as man of man,—yet in virtue of the ineffable unity of the mystery, by which man was joined to God, there is no separation between Christ and the Word? Hear the gospel of the Lord, or rather hear the Lord p. 576 Himself saying of Himself: 2458 “This,” says He, “is life eternal, that they may know Thee, the only true God, and Jesus Christ whom Thou hast sent.” 2459 You heard above that the Word of God was sent to heal mankind: here you are told that He who was sent is Jesus Christ. Separate this, if you can,—though you see that so great is the unity of Christ and the Word, that it was not merely that Christ was united with the Word, but that in virtue of the actual unity [of Person] Christ may even be said to be the Word.
Cf. Hooker Eccl: Polity., Book V. c. liii. § 4. “A kind of mutual commutation there is whereby those concrete names, God and man, when we speak of Christ, do take interchangeably one another’s room, so that for truth of speech it skilleth not whether we say that the Son of God hath created the world, and the Son of man by His death hath saved it, or else that the Son of man did create, and the Son of God die to save the world. Howbeit as oft as we attribute to God what the manhood of Christ claimeth, or to man what His Deity hath right unto, we understand by the name of God and the name of man neither the one nor the other nature, but the whole person of Christ, in whom both natures are.” The technical phrase by which this interchange of names is described is the Communicatio idiomatum, and in Greek ἀντίδοσις. Cf. Pearson on the Creed, Art. IV. c. i.
575:2457 576:2458De se dicentem (Petschenig): Gazæus reads descendentem.
576:2459S. John xvii. 3.