A judge informing Michael Vick that slaughtering dogs is a reprehensible crime didn't cause tears of regret to flow down the quarterback's cheeks. For whatever reason, Mr. Vick considers murdering cuddly pooches completely harmless. Through our judicial system, we can hopefully convince him to stay all future canine executions, but we cannot force the football superstar, or anybody else, to feel bad about an act he deems innocent.
Of course sane people would inherently feel sad about harming innocent creatures. Deep down, however, nothing else causes true regret. In other words, religion is strictly used to reverse instincts.
Just like Mr. Vick can't be made to feel empathy for the dogs, few religious people feel a bit of regret over "sins" that harm no one.
I bet there are thousands of gay Christians who don't beat themselves up for sharing a bed with a member of the same sex. Afterward, Sasha and Samantha look up at the ceiling and say, "That was bad for nobody, and extremely good for two!"
If sprinkling pepper was considered a horrific sin, and you hate pepper, you'd have no trouble condemning those needing a little spice. If blandness is not your thing, you'd secretly top your mashed potatoes with black specs. Afterward, your hot mouth wouldn't be a constant source of guilt for the simple reason that only happiness resulted. Regret doesn't stem from someone repeating in your ear, "You did a bad thing."
Religion is about illusion and denial. "Despite the fact that our guts say otherwise, we'll pretend certain actions are sins. Then we'll go to church and act as if we don't regularly, and without regret, perform these deeds. There, the preacher will speak against these 'crimes' as we nod our heads in agreement." You half-heartedly ask for forgiveness, trying your mightiest to pretend it's genuinely needed.
The person that formed the first organized religion probably sounded a lot like Homer Simpson...
"Most people don't daily do things they afterward regret, so we'll claim acts that hurt no one really hurt everyone. Then they'll feel guilty and give us money because only through us can they make amends for doing something perfectly fine that we've convinced them is reprehensible. Now, we just need a large structure in which to gather them all together to repeatedly remind them exactly how many crimes they've committed... Oh, and a bunch of plates so deep they resemble bowls. Then we're set!"
Trouble is, unlike most of Mr. Simpson's harebrained schemes, the above plot worked extraordinary well.