As therefore circumcision began with Abraham, and with Moses sabbath and sacrifices and offerings and feasts, and it has been proved that these were appointed because of the hardness of the heart of your people, it was thus requisite that they should cease, in accordance with the will of the Father, at the coming of Him who was born Son of God by means of the Virgin who was of the race of Abraham and the tribe of Judah and David, even Christ, who also was proclaimed as about to come as an everlasting Law and new Disposition for the whole world, as the prophecies which have been already stated signify.
And we who by Him drew near to God did not receive this circumcision according to the flesh, but one that is spiritual, which Enoch and those like him kept. But we received it by our baptism, since we had become sinners, because of the mercy that is from God, and all ought to receive it in like manner.
I turn to speak about the mystery of His birth, for this now claims our attention. Isaiah spake thus about the descent of Christ Himself, as has been already written, in proof that it cannot be described by men: Who shall declare His generation? For His life is taken from the earth, from the transgressions of my people was He led unto death. The prophetic spirit used these words to express the indescribable character of the descent of this Man who was about to die, that we sinful men might be healed by His stripes.
Further, that those who believe Him might be able to know the manner in which He has come into the world by birth, the spirit of prophecy prophesied as follows by the same Isaiah how it would be:
And the Lord spake again to Ahaz, saying: Ask thee a sign from the Lord thy God in the depth or in the height. And Ahaz said: I will not ask, nor will I tempt the Lord. And Isaiah said: Hear now, O House of David. Is it a small thing with you to propose a contest with men? And how do you propose a contest with the Lord? Therefore the Lord Himself shall give you a sign. Behold the virgin shall conceive and bring forth a son, and his name shall be called Emmanuel.
Butter and honey shall he eat. Before he knows or prefers evil he shall choose the good; because before the child knows good or ill, he refuses evil to choose the good. Because, before the child knows how to call father or mother he shall take away the power of Damascus and the spoil of Samaria in front of the king of the Assyrians. And the land shall be captured, which thou shalt bear with difficulty because of the two kings. And God shall bring upon thee, and upon thy people, and upon thy father’s house, days which have never yet come upon thee, from the day that Ephraim took away from Judah the king of the Assyrians.
Now that in the descent from Abraham according to the flesh no one has even been born, or said to have been born, of a virgin, save this our Christ, is evident to all.
But when you and your teachers dare to say that there is not even said in the prophecy of Isaiah: Behold the virgin shall conceive but ‘Behold the young woman shall conceive and bring forth a son,’ and ye expound the prophecy as referring to Hezekiah, who became your king, I will try in this particular to make a short exposition of it against you, and to prove that it has been said of Him whom we acknowledge to be Christ.