I have no qualms with anyone's beliefs so long as they don't use their beliefs as an excuse to hurt or subjugate others - if a man heard voices telling him to kill he'd be sectioned under the mental health act; just as I once was, religion doesn't make it okay.

Even if there was a god. And he was as real as the ground beneath your feet right now. And he told you to kill someone. You would still be wrong to kill someone (Or even just any bad thing) - just because a very powerful entity told you that it was okay didn't retroactively make what you did okay, you still did a bad thing.

I'd like to think (And I speak as an agnostic not an athiest) that if god told me "Slaughter your own kids or go to hell" I would choose to go to hell because, there is no dictator who will tell me what I can and can't do - supernatural powers or otherwise.

Power is not a justification. Not in religion, not in law, not in life.