1 This, therefore, having been clearly demonstrated here (and it shall yet be so still more clearly), that neither the prophets, nor the apostles, nor the Lord Christ in His own person, did acknowledge any other Lord or God, but the God and Lord supreme: the prophets and the apostles confessing the Father and the Son; but naming no other as God, and confessing no other as Lord: and the Lord Himself handing down to His disciples, that He, the Father, is the only God and Lord, who alone is God and ruler of all; — it is incumbent on us to follow, if we are their disciples indeed, their testimonies to this effect. For Matthew the apostle— knowing, as one and the same God, Him who had given promise to Abraham, that He would make his seed as the stars of heaven, and Him who, by His Son Christ Jesus, has called us to the knowledge of Himself, from the worship of stones, so that those who were not a people were made a people, and she beloved who was not beloved — declares that John, when preparing the way for Christ, said to those who were boasting of their relationship [to Abraham] according to the flesh, but who had their mind tinged and stuffed with all manner of evil, preaching that repentance which should call them back from their evil doings, said, “O generation of vipers, who has shown you to flee from the wrath to come? Bring forth therefore fruit meet for repentance. And think not to say within yourselves, We have Abraham [to our] father: for I say unto you, that God is able of these stones to raise up children unto Abraham.” He preached to them, therefore, the repentance from wickedness, but he did not declare to them another God, besides Him who made the promise to Abraham; he, the forerunner of Christ, of whom Matthew again says, and Luke likewise, “For this is he that was spoken of from the Lord by the prophet, The voice of one crying in the wilderness, Prepare the way of the Lord, make straight the paths of our God. Every valley shall be filled, and every mountain and hill brought low; and the crooked shall be made straight, and the rough into smooth ways; and all flesh shall see the salvation of God.” There is therefore one and the same God, the Father of our Lord, who also promised, through the prophets, that He would send His forerunner; and His salvation— that is, His Word — He caused to be made visible to all flesh, [the Word] Himself being made incarnate, that in all things their King might become manifest. For it is necessary that those [beings] which are judged do see the judge, and know Him from whom they receive judgment; and it is also proper, that those which follow on to glory should know Him who bestows upon them the gift of glory.
2. Then again Matthew, when speaking of the angel, says, “The angel of the Lord appeared to Joseph in sleep.” Of what Lord he does himself interpret: “That it may be fulfilled which was spoken of the Lord by the prophet, Out of Egypt have I called my son.” “Behold, a virgin shall conceive, and shall bring forth a son, and they shall call his name Emmanuel; which is, being interpreted, God with us.” David likewise speaks of Him who, from the virgin, is Emmanuel: “Turn not away the face of Your anointed. The Lord has sworn a truth to David, and will not turn from him. Of the fruit of your body will I set upon your seat.” And again: “In Judea is God known; His place has been made in peace, and His dwelling in Zion.” Therefore there is one and the same God, who was proclaimed by the prophets and announced by the Gospel; and His Son, who was of the fruit of David's body, that is, of the virgin of [the house of] David, and Emmanuel; whose star also Balaam thus prophesied: “There shall come a star out of Jacob, and a leader shall rise in Israel.” But Matthew says that the Magi, coming from the east, exclaimed “For we have seen His star in the east, and have come to worship Him;” and that, having been led by the star into the house of Jacob to Emmanuel, they showed, by these gifts which they offered, who it was that was worshipped; myrrh, because it was He who should die and be buried for the mortal human race; gold, because He was a King, “of whose kingdom is no end;” and frankincense, because He was God, who also “was made known in Judea,” and was “declared to those who sought Him not.”
3. And then, [speaking of His] baptism, Matthew says, “The heavens were opened, and He saw the Spirit of God, as a dove, coming upon Him: and lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.” For Christ did not at that time descend upon Jesus, neither was Christ one and Jesus another: but the Word of God— who is the Saviour of all, and the ruler of heaven and earth, who is Jesus, as I have already pointed out, who did also take upon Him flesh, and was anointed by the Spirit from the Father— was made Jesus Christ, as Esaias also says, “There shall come forth a rod from the root of Jesse, and a flower shall rise from his root; and the Spirit of God shall rest upon Him: the spirit of wisdom and understanding, the spirit of counsel and might, the spirit of knowledge and piety, and the spirit of the fear of God, shall fill Him. He shall not judge according to glory, nor reprove after the manner of speech; but He shall dispense judgment to the humble man, and reprove the haughty ones of the earth.” And again Esaias, pointing out beforehand His unction, and the reason why he was anointed, does himself say, “The Spirit of God is upon Me, because He has anointed Me: He has sent Me to preach the Gospel to the lowly, to heal the broken up in heart, to proclaim liberty to the captives, and sight to the blind; to announce the acceptable year of the Lord, and the day of vengeance; to comfort all that mourn.” For inasmuch as the Word of God was man from the root of Jesse, and son of Abraham, in this respect did the Spirit of God rest upon Him, and anoint Him to preach the Gospel to the lowly. But inasmuch as He was God, He did not judge according to glory, nor reprove after the manner of speech. For “He needed not that any should testify to Him of man, for He Himself knew what was in man.” For He called all men that mourn; and granting forgiveness to those who had been led into captivity by their sins, He loosed them from their chains, of whom Solomon says, “Every one shall be holden with the cords of his own sins.” Therefore did the Spirit of God descend upon Him, [the Spirit] of Him who had promised by the prophets that He would anoint Him, so that we, receiving from the abundance of His unction, might be saved. Such, then, [is the witness] of Matthew.
Source: Adversus haereses (New Advent)