The atrocity in Norway highlights some profound questions about moral law that are important in the discussion about atheism and theism. I assert that only theism is consistent with the existence of objective moral law.
I suspect that some atheists have a problem understanding what I mean by "objective" moral law.
I mean moral law that:
2) Was not made by humans
3) Can be obeyed or disobeyed by humans.
If we define evil as defective 'mirror neurons', or a particularly unpleasant evolutionary adaptation, we mean that evil is subjective, and exists only in our minds. Of course, a subjective moral law can be widely and even universally held, but it has no reality independent of human minds.
So here's a question that gets to the heart of the issue:
Could something be evil, even if all human beings thought it was good?
If yes, then moral law is objective reality. If no, then moral law is entirely subjective.
Only theism offers an explanation for objective moral law. If atheism is true, then all moral law is just a matter of opinion, even the moral status of murdering children at a summer camp.