The God Delusion is a 2006 best-selling non-fiction book by English biologist Richard Dawkins, professorial fellow of New College, Oxford, and former holder of the Charles Simonyi Chair for the Public Understanding of Science at the University of Oxford.
In The God Delusion, Dawkins contends that a supernatural creator almost certainly does not exist and that belief in a personal god qualifies as a delusion, which he defines as a persistent false belief held in the face of strong contradictory evidence. He is sympathetic to Robert Pirsig's statement in Lila (1991) that "when one person suffers from a delusion it is called insanity. When many people suffer from a delusion it is called religion." With many examples, he explains that one does not need religion to be moral and that the roots of religion and of morality can be explained in non-religious terms.
In early December 2006, it reached number four in the New York Times Hardcover Non-fiction Best Seller list after nine weeks on the list.
The book has attracted widespread commentary, with many books written in response.