Because that is the way sky-daddy talks to his earth-kids.
It's a way of making those who want to think for themselves, feel guilty at every angle the can. This is a cult programing technique, and because SO many are followers of Chrisitanity, it's deemed as a religion.
It's an uphill battle to try to come up with a new faith now-a-days, this is why I'm still amazed at Scientology, how new that is, and rounded up so many people with a story that was displayed, as is, on South Park in the episode "Trapped in the Closest"
Total headshaker...