"You're overlooking that the only reason something is a sin is because "god" says so. When some steals $10,000, yeah some is out of money and there is harm. When someone sins, it's only a sin because god says so, and god has not been harmed. (If God was harmed, he wouldn't be omnipotent, would he?) So, god merely has to stop saying it's a sin and there's no more sin. "

Sin is something that God cannot do, and being keen on justice, He can't let people off. If God had intended there to be no sin, then there wouldn't be. He allowed it, for His own purposes, like seeing if people would choose God or choose sin.