Nicene and Post-Nicene Fathers, Ser. II, Vol. XI:
The Works of John Cassian.: Chapter XVI. He brings forward the witness of God the Father to the Divinity of the Son.

Chapter XVI.

He brings forward the witness of God the Father to the Divinity of the Son.

What do you say now, you heretic? Are these evidences of the faith, aye and of all your unbelief, enough for you: or would you like some more to be added to them? but what can be added after Prophets and Apostles? unless perhaps—as the Jews once demanded—you too might ask for a sign to be given you from heaven? But if you ask this, we must give you the same answer which was formerly given to them: “An evil and adulterous generation seeketh after a sign. And no sign shall be given to it, but the sign of the prophet Jonah.” 2446 And indeed this sign would be enough for you as for the Jews who crucified Him, that you might be taught to believe in the Lord God by this alone, through which even those who had persecuted Him, came to believe. But as we have mentioned a sign from heaven, I will show you a sign from heaven: and one of such a character that even the devils have never gainsaid it: while, constrained by the demands of truth, though they saw Jesus in bodily form, they yet cried out that He was God, as indeed He was. What then does the Evangelist say of the Lord Jesus Christ? “When He was baptized,” he says, “straightway He went up out of the water. And lo, the heavens were opened to Him, and He saw the Spirit descending like a dove, and coming upon Him. And behold, a voice from heaven, saying: This is My beloved Son, in whom I am well pleased.” 2447 What do you say to this, you heretic? Do you dislike the words spoken, or the Person of the Speaker? The meaning of the utterance at any rate needs no explanation: nor does the worth of the Speaker need the commendation of words. It is God the Father who spoke. What He said is clear enough. Surely you cannot make so shameless and blasphemous an assertion as to say that God the Father is not to be believed concerning the only begotten Son of God? “This,” He then says, “is My beloved Son in whom I am well pleased.” But perhaps you will try to maintain that this is madness, and that this was said of the Word and not of Christ. Tell me then who was it who was baptized? The Word or Christ? Flesh or Spirit? You cannot possibly deny that it was Christ. That man then, born of man and of God, conceived by the descent of the Holy Spirit upon the Virgin, and by the overshadowing of the Power of the Most High, and thus the Son of man and of God, He it was, as you cannot deny, who was baptized. If then it was He who was baptized, it was He also who was named, for certainly the Person who was baptized was the one named. “This,” said He, “is My beloved Son, in whom I am well pleased.” Could anything be said with greater significance or clearness? Christ was baptized. Christ went up out of the water. When Christ was baptized the heavens were opened. For Christ’s sake the dove descended upon Christ, the Holy Spirit was present in a bodily form. The Father addressed Christ. If you venture to deny that this was spoken of Christ, the only thing is for you to maintain that Christ was not baptized, that the Spirit did not descend, and that the Father did not speak. But the truth itself is urgent and weighs you down so that even if you will not confess it, yet you cannot deny it. For what says the Evangelist? “When He was baptized, straightway He went up out of the water.” Who was baptized? Most certainly Christ. “And behold,” he says, “the heavens were opened to Him.” To where, forsooth, save to Him who was baptized? Most certainly to Christ. “And He saw the Spirit of God descending like a dove and coming upon Him.” Who saw? Christ indeed. Upon whom did It descend? Most certainly upon Christ. “And a voice came from heaven. saying”—of whom? Of Christ indeed: for what follows? “This is My beloved Son, in whom I am well pleased.” In order that it might be made clear on whose account all this happened, there followed the voice, saying: “This is My beloved Son,” as if to say: This is He on whose account all this took place. For this is My Son: on His account the heavens were opened: on His account My Spirit came: on His account My voice was heard. For this is My Son. In saying then “This is My Son” whom did He so designate? Certainly Him whom the dove touched.  And whom did the dove touch? Christ indeed. Therefore Christ is the Son of God. My promise is fulfilled, I fancy. Do you see p. 573 then now, O heretic, a sign given you from heaven; and not one only, but many and special ones? For there is one in the opening of heaven, another in the descent of the Spirit, a third in the voice of the Father. All of which most clearly show that Christ is God, for the laying open of the heavens indicates that He is God, and the descent of the Holy Spirit upon Him supports His Divinity, and the address of the Father confirms it. For heaven would not have been opened except in honour of its Lord: nor would the Holy Ghost have descended in a bodily form except upon the Son of God: nor would the Father have declared Him to be the Son, had he not been truly such; especially with such tokens of a Divine birth, as not merely to confirm the truth of the right faith, but also to exclude the wickedness of guilty and erroneous belief. For when the Father had expressly and pointedly said with the inexpressible majesty of a Divine utterance, “This is My Son,” He added also what follows—I mean, “My beloved, in whom I am well pleased.” As He had already declared Him by the prophet to be God the Mighty and God the Great, so when He says here, “My beloved Son in whom I am well pleased,” He adds further to the name of His own Son the title also of His beloved Son, in whom He is well pleased: that the addition of the titles might denote the special properties of the Divine nature; and that that might specially redound to the glory of the Son of God, which had never happened to any man. And so just as in the case of our Lord Jesus Christ these special and unique things happened; viz., that the heavens were opened, that in the sight of all God the Father touched Him in a sort of way, through the coming and presence of the dove, and pointed almost with His finger to Him saying, “This is My Son;” so this too is special and unique in His case; viz., that He is specially beloved, and is specially named as well-pleasing to the Father, in order that these special accompaniments might mark the special import of His nature, and that the special character of His names might support the special position of the only begotten Son, which the honour of the signs previously given had already confirmed. But here comes the end of this book. For this saying of God the Father can neither be added to, nor equalled by any words of men. For us God the Father Himself is a sufficiently satisfactory witness concerning our Lord Jesus Christ, when He says “This is My Son.” If you think that it is possible for these utterances of God the Father to be gainsaid, then you are forced to contradict Him, who by the clearest possible announcement caused Him to be acknowledged as His Son by the whole world.

Footnotes

S. Matt. xvi. 4.

S. Matt. 3:16, 17.