Good and Evil

[bennyboy]

For example, sex.  There's nothing really wrong with it...

Perhaps not "wrong." But sex is hardly a benign feature of evolutionary history. It keeps the species going, but usually at the detriment of the individual. Such creatures as salmon literally die to get their rocks off. Within human societies, our freedom to choose partners for love and seek pleasurable self-fulfillment through sexual enactments of our own choosing is a recent phenomenon, going back no further than the 18th century in the Western world.

Exactly.  So part of the moral code of sex, even for non-religious people, is that we struggle to mediate our animal desires with our human ability to consider consequences.  If you're married, it's immoral to fuck someone else-- not because you're that likely to actually impregnate someone or get a disease (if you're careful at least), but because your wife ALSO has animal instincts, and your failure to control your instinct is almost certainly going to trigger a god-awful emotional (read: animal) reaction in her.

And while you are spending time and resources chasing some ho, paying her off so she won't tell your wife, promising her that someday, you'll separate from your wife, telling your wife you're going to the bar and then explaining why your friends called to ask if you were free to come out, etc. etc., and while your wife is investigating, getting stressed, discovering the truth, getting furious, divorcing you, telling your kids what a prick you are, etc. etc. what are none of you doing? Taking positive steps toward achieving your potential in life.