There are contrasting theories that deal with different aspects of human religiosity - some focus on religious beliefs, while others focus on religious actions, and still others on the origin of religious ideas. While these theories might share a similar focus, there is plenty of disagreement in the explanations they offer. This volume examines the diversity of new scientific theories of religion, by outlining the logical and causal relationships between these enterprises. Are they truly in competition, as their proponents sometimes suggest, or are they complementary and mutually illuminating accounts of religious belief and practice?