Albert Barnes' Notes on the Whole Bible - 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;... read more
The Pulpit Commentary - 1 Corinthians 6:18
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,... read more