How the West Really Lost God, by Mary Eberstadt

Mary Eberstadt presents a convincing theory that family formation and family life help to pass on and enforce religious belief from one generation to the next rather than just being an effect of religious belief. She points out how marriage, family formation, and birth rates tend to rise and fall in tandem with religious practice among populations, and how this correlation tends to hold more consistently through history than other explanations of why belief in God rises and falls, such as political or economic changes, wars, industrialization, etc. The book can be a dry read at times, because it does deal with statistics, but very worthwhile for those who are interested in the subject.