The rest of The God Delusion is generally more speculative. If God or gods almost certainly do not exist, then why is religion so embedded in human culture? Dawkins sketches a review of some possible answers, but his preferred hypothesis is this: Religion does not confer a direct adaptive advantage, but is instead a byproduct of some other property that is useful for survival.
Dawkins, however, is no crank, and he is not proposing the abolition of religion, but rather that we acquire a proper perspective on it. Religion is a cultural heritage that should be appreciated for its contributions to history, literature, and art, and Dawkins actually advocates more education in the subject. At the same time, its promotion as a guide to absolute truth, as a dogmatic and authoritarian prescription for behavior, and as a substitute for scientific thinking, leads to catastrophic excesses and false conclusions, which he documents at length. We can respect poetry as a window on the human mind and an outlet for the expression of beauty, but we’d laugh at someone who claimed that poetry explained cosmology, was grounds for declaring war, or could cure cancer. But religion makes these kinds of claims, and a dangerous majority accepts them. Dawkins asks that we recognize religion as a legitimate expression of human feeling-but that we avoid overendowing it with powers it does not possess.