How sinful is it for a man to look at beautiful women?

This is one of those ‘beauty and the beast’ things: On the one hand, the female form is one of the most aesthetically pleasing things God ever designed. The Renaissance artists understood this; many of them were fine Christians. There is a difference, however, between appreciating the aesthetics of the feminine form and getting hooked by one’s own lust. (Those who have drawn nudes in college know the difference: the models are almost never seductive in their demeanor or behavior, but they are always aesthetically pleasing.)

On the other hand, skimpily-clad women often, if not usually, attempting to catalyze more than aesthetic pleasure! One cannot look into another’s heart; therefore, it is quite impossible to say something like “Looking once is OK, but a second look is sinful.” It depends on both people—the looker and the lookee.

But it also depends on one other factor: There is certain dress that really ought to be kept private, within marriage (e.g., see-through clothing, lingerie, Brazilian-cut bathing suits, etc.). One may well fool himself into thinking that he’s only gazing at such things in public for its aesthetic value, when in reality he is getting drawn into a trap by his own lusts. We are told in scripture to flee from lusts of the flesh. This is one battle that we cannot win; it is always better to run when faced with such temptations. One needs only to read the book of Proverbs to see how much material there is on the problems of lust, fornication, adultery, etc.