Ambrosiaster : For, as it is said, the one who joins himself to a prostitute is one body with her. Sexual immorality joins them together as one, just as in nature, two become one. As it is written, 'They shall become one flesh' (Genesis 2:24). It is clear that because the woman is from the man, both are one flesh. — Commentary on 1 Corinthians John Chrysostom : Then he makes out how the fornicator becomes this, saying thus, "Know ye not that he that is joined unto a harlot is one body?" How is this evident? "For the twain, saith He, shall become one." For the conjunction suffers the two no longer to be two, but makes them both one. — Homily on 1 Corinthians 18 Oecumenius : A man guilty of fornication and the impurity which comes from it insults his marriage and his wife. He sins against his own body and consequently against his wife, because the two are one flesh. — PAULINE COMMENTARY FROM THE GREEK CHURCH