Expositor's Bible Commentary Commentary 1 Corinthians 6:18

"Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body." — 1 Corinthians 6:18 (ASV)

Those who commit sexual immorality sin against their own body—that is, by weakening and perverting the very life process, as well as human character. In contrast, other sins are “outside the body.” From such sins Christians should be continually fleeing.