Can a person be moral without God?

Mike Flynn's Thomistic approach is better than anything I've heard in a bunch of debates on the subject.

Mark Shea offers this gloss:

In the course of it, we discover a) that Fundamentalist Christians who imagine that morality is impossible for an atheist simple do not know what they are talking about. However, we also discover that atheist moralists (aka "New Atheists") have not thought deeply at all about the untenableness of their own position. Real atheists are actually the ones who argue the most strenuously that morality is a subjective illusion, that there is no answer to the question "Why not be cruel?" without smuggling in a transcendent code of ethics reflecting the Will of You Know Who, and so forth. So the problem is not that atheists are immoral. The problem is that atheists are theives who constantly borrow Greatest Hits from a transcendent worldview rooted in Theism, while lying to everybody (including themselves) that their favorite "self-evident" truths are just artifacts of evolution or "practical" or some other lame naturalist piece of bafflegab while ignoring the fact that they are privileging their own favorite moral precepts as Transcendent.