{12} What? know ye not that he which is joined to an harlot is one body? for {i} two, saith he, shall be one flesh.

(12) A proof of the same argument: a harlot and Christ are completely contrary, so are the flesh and the Spirit. Therefore he that is one with a harlot (which is done by sexual intercourse with their bodies) cannot be one with Christ, which unity is pure and spiritual.

(i) Moses does not speak these words about fornication, but about marriage: but seeing that fornication is the corruption of marriage, and both of them are a carnal and fleshly copulation, we cannot say that the apostle abuses his testimony. Again, Moses does not have this word two, but it is very well expressed both here and in Mt 19:5, because he speaks only of man and wife: whereupon the opinion of those that vouch it to be lawful to have many wives is overthrown: for he that companies with many, is broken as it were into many parts.

Wesley's Notes

6:16 Gen 2:24.

Jamieson-Fausset-Brown Bible Commentary

16. Justification of his having called fornicators "members of an harlot" (1Co 6:15).

joined-by carnal intercourse; literally, "cemented to": cleaving to.

one body-with her.

saith he-God speaking by Adam (Ge 2:24; Mt 19:5). "He which made them at the beginning said," &c. (Eph 5:31).

Matthew Henry's Concise Commentary

6:12-20 Some among the Corinthians seem to have been ready to say, All things are lawful for me. This dangerous conceit St. Paul opposes. There is a liberty wherewith Christ has made us free, in which we must stand fast. But surely a Christian would never put himself into the power of any bodily appetite. The body is for the Lord; is to be an instrument of righteousness to holiness, therefore is never to be made an instrument of sin. It is an honour to the body, that Jesus Christ was raised from the dead; and it will be an honour to our bodies, that they will be raised. The hope of a resurrection to glory, should keep Christians from dishonouring their bodies by fleshly lusts. And if the soul be united to Christ by faith, the whole man is become a member of his spiritual body. Other vices may be conquered in fight; that here cautioned against, only by flight. And vast multitudes are cut off by this vice in its various forms and consequences. Its effects fall not only directly upon the body, but often upon the mind. Our bodies have been redeemed from deserved condemnation and hopeless slavery by the atoning sacrifice of Christ. We are to be clean, as vessels fitted for our Master's use. Being united to Christ as one spirit, and bought with a price of unspeakable value, the believer should consider himself as wholly the Lord's, by the strongest ties. May we make it our business, to the latest day and hour of our lives, to glorify God with our bodies, and with our spirits which are his.