I'm going to give this a shot. #1: The Varieties of Scientific Experience: A Personal View of the Search for God, by Carl Sagan and Ann Druyan A posthumous printing of Sagan's 1985 Gifford Lecture. He begins with a detailed examination of cosmology and discusses all sorts of things: pseudoscience, astrophysics, intelligent design, etc. He goes through theistic proofs and demolishes them; the arguments he uses aren't new but it's a concise summary of those proofs. He argues, pretty effectively, that the feelings we attain from religious experience are equally powerful in science. The rational discovery of truths and a reason-based appraoch to the world can be very stimulating, which I think is true. Like all of Carl's work it is elegant, concise, and profound. Seriously, the world is poorer without him.