I just watched the one and a half hour debate between Christian theist Dinesh D'Souza and anti-theist Christopher Hitchens on "Is Christianity the Problem?"
This debate is interesting, spirited and lively, a lot of fun to watch. You can see the entire thing here.
Watch Hitchens, at minute 37, raise the objection that if atheism is true than there is no metaphysical foundation for ethics. Hitchens speaks as if it's only theists who have raised this objection. But Nietzsche recognized it, as it seems Bertran Russell also did in his "A Free Man's Worship." After raising this objection Hitchens never really answers it but rather does, it seems to me, a tu quoque, pointing out how religious teachings seem self-contradictory. The question Hitchens raises is a good one. But he never answers it. I think it's because, on atheism, it cannot be answered.