Because our rules are better. Stoning gays, killing 2,000,000+, ordering women to worship men...yeah, God sounds like a swell guy.
The law of Moses was incredibly progressive for its time. God was working within the context of ancient Mesopotamia. For example, the law demanding that any man who sleeps with an unmarried woman (which was often rape) must marry her may seem unfair, demeaning, and even barbaric to modern society, but in a society where the only way a woman could get by was through her husband, and no man wanted to marry a non-virgin, it was the most merciful thing that could be done for her until society as a whole changed drastically. Blindly comparing Leviticus to modern times without looking at it in a historical and cultural context, whether it's a Christian trying to apply every law to today or a skeptic trying to show how evil God is, is irresponsible. The former assumes that ancient Mesopotamian culture is a perfect ideal which must be applied to everyone; the latter assumes the same about modern Western culture. Both are transcended by "love God, love your neighbor."
However, the more fundamental issue at hand, and the one that everyone except Turtlekid and Weegee has been pretending doesn't exist for like three pages now, is this: By whose standards are your rules better? WHY are they better? Most basically,
what does "better" even mean? Is there some universal ought-ness to it (if so, where does your authority come from?), or is it just personal preference (if so, why are we arguing about it like it matters?)?
Side note: If you believe that God doesn't exist and the Bible was written by humans, then you obviously believe that humans can screw up really bad when making moral laws (although "screwing up" implies that there's some higher standard, whose origin you don't seem to be able to account for, against which moral laws are compared). How can you ensure your rules are better, when you're just as human as they were?
