Starting with Freud and his "projection theory" of religion, psychoanalysts have argued that belief in God is merely a product of man’s desire for security. In this updated, expanded edition, Professor Vitz argues that psychoanalysis actually provides a more satisfying explanation for atheism: disappointment in one’s earthly father, whether through death, absence, or mistreatment, frequently leads to a rejection of God. A biographical survey of influential atheists of the past four centuries shows that this "defective father hypothesis" provides a consistent explanation of the intense atheism of these thinkers. A survey of the leading defenders of Christianity over the same period confirms the hypothesis. Professor Vitz does not argue that atheism is psychologically determined. Each man, whatever his experiences, ultimately chooses to accept God or to reject him. Paper.