Greg Graffin is frontman, singer and songwriter for the punk band Bad Religion. He also happens to have a Ph.D. in zoology and wrote his dissertation on evolution, atheism and naturalism. Preston Jones is a history professor at a Christian college and a fan of Bad Religion's music. One day, on a whim, Preston sent Greg an appreciative e-mail. That was the start of an extraordinary correspondence. For several months, Preston and Greg sent e-mails back and forth on big topics like God, religion, knowledge, evil, evolution, biology, destiny and the nature of reality. Preston believes in God; Greg sees insufficient evidence for God's existence. Over the course of their friendly debate, they tackle such cosmic questions as: Is religion rational or irrational? Does morality require belief in God? Do people only believe in God because they are genetically predisposed toward religion? How do you make sense of suffering in the world? Is this universe all there is? And what does it all matter? In this engaging book, Preston and Greg's actual e-mail correspondence is reproduced, along with bonus materials that provide additional background and context. Each makes his case for why he thinks his worldview is more compelling and explanatory. While they find some places to agree, neither one convinces the other. They can't both be right. So which worldview is more plausible? You decide.