Tractates on the Gospel of John

^7. He that is born of the Catholic Church, is born, as it were, of Sarah, of the free woman; he that is born of heresy is, as it were, born of the bond woman, but of Abraham's seed. Consider, beloved, how great a mystery. God testifies, saying, “I am the God of Abraham, and the God of Isaac, and the God of Jacob.” Were there not other patriarchs? Before these, was there not holy Noah, who alone of the whole human race, with all his house, was worthy to be delivered from the flood,— he in whom, and in his sons, the Church was prefigured? Borne by wood, they escaped the flood. Then afterwards great men whom we know, whom Holy Scriptures commends, Moses faithful in all his house. And yet those three are named, just as if they alone deserved well of him: “I am the God of Abraham, and the God of Isaac, and the God of Jacob: this is my name for ever.” Sublime mystery! It is the Lord that is able to open both our mouth and your hearts, that we may speak as He has deigned to reveal, and that you may receive even as it is expedient for you.