The Reason for God by Timothy Keller
My wife and I used to go to Redeemer Presbyterian [Church] in Manhattan, where Keller is a pastor. I knew he wrote a bunch of books, and this is one of the first I picked up. I grew up in a Christian household, and this book opened things up and made me look at God in another way — that God can be a rational thought.
I think my older brother Eric gave this book to me — he reads more than I do.