John Chrysostom
How is this so? He came from our nature, just as Eve is flesh from Adam’s flesh. He mentioned bones and flesh because these are chief in us, flesh and bones. One is, as it were, the foundation, the other the building.
That point is clear. But how is this other point so? As there is great closeness there, he says, so also here. What does “of His flesh” mean? It means truly from Him.
But how do we thereby become members of Christ? We do so because we have been born like Him. How are we of His flesh? You who partake of the Mysteries know this, for through them we are immediately formed after His pattern.
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But how? First hear what the blessed Paul says: “Since the children have partaken of flesh and blood, He Himself likewise shared in the same” (Heb 2:14). Yet here He partook of us, not we of Him.
How, then, are we “of His flesh and of His bones”? Some refer here to the blood and the water, but that is not correct. He willed to show this: as He was born of the Holy Spirit without intercourse, so we too are born in the font.
See how many examples lead us to believe that birth. O madness of the heretics! What is born of water they acknowledge as a true birth. Yet they do not accept that we become His body.
But if we do not become it, how shall we reconcile this with the words, “of His flesh and of His bones”? And observe: Adam was fashioned, Christ was born. From Adam’s rib came corruption. From Christ’s side flowed life.
In Paradise death sprang up. On the Cross it was destroyed. Therefore, as the Son of God is of our nature, so we are of His substance. As He has us in Himself, so we have Him in ourselves.