1 Corinthians 6:18

Flee fornication - A solemn command of God - as explicit as any that thundered from Mount Sinai. None can disregard it with impunity - none can violate it without being exposed to the awful vengeance of the Almighty. There is force and emphasis in the word “flee” φεύγατε pheugate. Man should escape from it; he should not stay to reason about it; to debate the matter; or even to contend with his propensities, and to try the strength of his virtue. There are some sins which a man can resist; some about which he can reason without danger of pollution. But this is a sin where a man is safe only when he flies; free from pollution only when he refuses to entertain a thought of it; secure when he seeks a victory by flight, and a conquest by retreat. Let a man turn away from it without reflection on it and he is safe. Let him think, and reason, and he may be ruined. “The very passage of an impure thought through the mind leaves pollution behind it.” An argument on the subject often leaves pollution; a description ruins; and even the presentation of motives against it may often fix the mind with dangerous inclination on the crime. There is no way of avoiding the pollution but in the manner prescribed by Paul; there is no man safe who will not follow his direction. How many a young man would be saved from poverty, want, disease, curses, tears, and hell, could these two words be made to blaze before him like the writing before the astonished eyes of Belshazzar Daniel 5, and could they terrify him from even the momentary contemplation of the crime.

Every sin ... - This is to be taken comparatively. Sins in general; the common sins which people commit do not immediately and directly affect the body, or waste its energies, and destroy life. Such is the case with falsehood, theft, malice, dishonesty, pride, ambition, etc. They do not immediately and directly impair the constitution amid waste its energies.

Is without the body - Does not immediately and directly affect the body. The more immediate effect is on the mind; but the sin under consideration produces an immediate and direct effect on the body itself.

Sinneth against his own body - This is the FourTH argument against indulgence in this vice; and it is more striking and forcible. The sense is, “It wastes the bodily energies; produces feebleness, weakness, and disease; it impairs the strength, enervates the man, and shortens life.” Were it proper, this might be proveD to the satisfaction of every man by an examination of the effects of licentious indulgence. Those who wish to see the effects stated may find them in Dr. Rush on the Diseases of the Mind. Perhaps no single sin has done so much to produce the most painful and dreadful diseases, to weaken the constitution, and to shorten life as this. Other vices, as gluttony and drunkenness, do this also, and all sin has some effect in destroying the body, but it is true of this sin in an eminent degree.