What are the biological roots of our religious sense? What does it mean to have religious qualities deeply embedded in our human nature and imposed by our biology? Do we need them? What can we make of the fact that each of our decision's to be religious or irreligious is one of the most defining decisions of our lives yet may be due to a neurotransmitter hiccup or a genetic influence? What does it mean that some people's biology causes them to lose faith yet for others their biology builds their faith?