(18) Flee fornication.--These last three verses of the chapter contain a solemn exhortation to purity, arising out of the previous argument.

Without the body.--The word "body" is still to be understood as used of the whole "human nature," which is spoken of in 1Corinthians 6:19 as the temple of the Holy Ghost. Other sins may profane only outer courts of the temple; this sin penetrates with its deadly foulness into the very holy of holies--

"It hardens a' within, and petrifies the feelings."

There is a deep significance and profound truth in the solemn words of the Litany, "From fornication, and all other deadly sin, good Lord, deliver us."

Verse 18. - Flee fornication. In the battle against sensual sins, there is no victory except in absolute flight, for the reason which immediately follows, namely, that these sins have their dwelling in that body which is part of our being, and which yet they tend to destroy. They make a man his own deadliest enemy. Every sin... is without the body. Some have supposed that this cannot apply to gluttony and drunkenness, which they therefore class with fornication; but even in those sins, as in suicide, the cause of and incentive to the sin is external, whereas the source of uncleanness is in the heart and in the thoughts, which come from within, and so defile the man. Other sins may be with and by means of the body, and may injure the body; but none are so directly against the sanctity of the whole bodily being as fornication. Sinneth against his own body. By alienating it from the service of him to whom it belongs; by incorporating it with the degradation of another; by staining the flesh and the body (Proverbs 5:8-11; Proverbs 6:24-32; Proverbs 7:24-27); by subtly poisoning the inmost sanctities of his own being. St. Paul is here thinking mainly, however, if not exclusively, of the moral injury and defilement.

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.Flee fornication,.... As that which is hurtful, scandalous, and unbecoming Christians; avoid it, and all the occasions of it, that may lead unto it, and be incentives of it:

every sin that a man doth is without the body not but that other sins are committed by the body, and by the members of it as instruments; they are generally committed by the abuse of other things that are without, and do not belong to the body; and so do not bring that hurt unto and reproach upon the body, as fornication does:

but he that committeth fornication, sinneth against his own body; not meaning his wife, which is as his own body; but his proper natural body, which is not only the instrument by which this sin is committed, but the object against which it is committed; and which is defiled and dishonoured by it; and sometimes its strength and health are impaired, and it is filled with nauseous diseases hereby.