In The Blind Watchmaker, Dawkins asserts that the theory of evolution makes is possible to be an "intellectually satisfied atheist". Personally, I think this is nonsense, in the absense of positive evidence for a deity, there is no logical alternative to atheism, whether or not we can explain the diversity of life on Earth. Of course it does make it easier to debate with some theists, who won't take "How the fuck should I know?" for an answer.