4 Let us, as I said, see how he is confuted, and then let us set forth the truth. Now he quotes the words, “Egypt has laboured, and the merchandise of Ethiopia and the Sabeans,” and so forth on to the words, “For You are the God of Israel, the Saviour.” And these words he cites without understanding what precedes them. For whenever they wish to attempt anything underhand, they mutilate the Scriptures. But let him quote the passage as a whole, and he will discover the reason kept in view in writing it.
For we have the beginning of the section a little above; and we ought, of course, to commence there in showing to whom and about whom the passage speaks. For above, the beginning of the section stands thus: “Ask me concerning my sons and my daughters, and concerning the work of my hands, command me. I have made the earth, and man upon it: I with my hand have established the heaven; I have commanded all the stars. I have raised him up, and all his ways are straight. He shall build my city, and he shall turn back the captivity; not for price nor reward, said the Lord of hosts.
Thus said the Lord of hosts, Egypt has laboured, and the merchandise of Ethiopia and the Sabeans, men of stature, shall come over unto you, and they shall be slaves to you: and they shall come after you bound with manacles, and they shall fall down unto you; and they shall make supplication unto you, because God is in you; and there is no God beside you. For You are God, and we knew not; the God of Israel, the Saviour,” “In you, therefore,” says he, “God is.” But in whom is God except in Christ Jesus, the Father's Word, and the mystery of the economy?
And again, exhibiting the truth regarding Him, he points to the fact of His being in the flesh when He says, “I have raised Him up in righteousness, and all His ways are straight.” For what is this? Of whom does the Father thus testify? It is of the Son that the Father says, “I have raised Him up in righteousness.” And that the Father did raise up His Son in righteousness, the Apostle Paul bears witness, saying, “But if the Spirit of Him that raised up Christ Jesus from the dead dwell in you, He that raised up Christ Jesus from the dead shall also quicken your mortal bodies by His Spirit that dwells in you.”
Behold, the word spoken by the prophet is thus made good, “I have raised Him up in righteousness.” And in saying, “God is in you,” he referred to the mystery of the economy, because when the Word was made incarnate and became man, the Father was in the Son, and the Son in the Father, while the Son was living among men. This, therefore, was signified, brethren, that in reality the mystery of the economy by the Holy Ghost and the Virgin was this Word, constituting yet one Son to God.
And it is not simply that I say this, but He Himself attests it who came down from heaven; for He speaks thus: “No man has ascended up to heaven, but He that came down from heaven, even the Son of man which is in heaven.” What then can he seek beside what is thus written? Will he say, forsooth, that flesh was in heaven? Yet there is the flesh which was presented by the Father's Word as an offering,— the flesh that came by the Spirit and the Virgin, (and was) demonstrated to be the perfect Son of God.
It is evident, therefore, that He offered Himself to the Father. And before this there was no flesh in heaven. Who, then, was in heaven but the Word unincarnate, who was dispatched to show that He was upon earth and was also in heaven? For He was Word, He was Spirit, He was Power. The same took to Himself the name common and current among men, and was called from the beginning the Son of man on account of what He was to be, although He was not yet man, as Daniel testifies when he says, “I saw, and behold one like the Son of man came on the clouds of heaven.” Rightly, then, did he say that He who was in heaven was called from the beginning by this name, the Word of God, as being that from the beginning.
Source: Against the Heresy of Noetus (New Advent)