In "The God Delusion", Dawkins contends that a supernatural creator, God, 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 "" (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.