Sacrifice - ranging from the sacrifice of virgins to circumcision to giving up what is most valued - is essential to all religions. Could there be a natural, even biological, reason? Why are sacrifice and numerous other religious rituals and concepts shared by so many different cultures? In this book, the author explores the possibility of natural religion. It provides insight to religious thought, past and present, and raises questions about the ultimate reasons for, and the ultimate meaning of human religiousness.