The reason why thinking ability is essential in maintaining moral purity in an unclean world is that the ways of an immoral person are seductive. Solomon warns: “As a honeycomb the lips of a strange woman keep dripping, and her palate is smoother than oil. But the aftereffect from her is as bitter as wormwood; it is as sharp as a two-edged sword.”​—Proverbs 5:3, 4.

The aftereffects of immorality are as bitter as wormwood and as sharp as a two-edged sword​—painful and death dealing. A troubled conscience, an unwanted pregnancy, or a sexually transmitted disease are often the bitter consequences of such conduct. And think of the enormous emotional pain experienced by the marriage partner of an unfaithful individual. One act of infidelity can inflict wounds deep enough to last a lifetime. Yes, immorality hurts.