It's a subject that's been gone over many times, but I think Steven Novella put up a good post.
I especially like the part where he points out something that I should have realized myself: Non-theistic morality is inherently more objective than divine command theory. Why?
First, moral philosophy is a transparent process where anyone can find out why some things are considered good or evil. There are first principles and rules that are derived from those principles. By having everyone asking questions about the process, you tend to reduce individual biases.
Second, because of all the conflicts between religions and even priests within a religion. There are countless interpretations of holy books. Even if there were some magic man giving out an objective morality, what would the basis of those decisions be? Divine command theory just strikes me as a morality without any basis whatsoever. As far as I'm concerned, it's objectively random morality before you add any subjective interpretation by humans.