The primary debate among scholars who study the evolution of religion concerns whether religion is an adaptation or a byproduct. The dominant position in the field is that religious beliefs and behaviors are byproducts of cognitive processes and behaviors that evolved for other purposes. A smaller group of scholars maintain that religion is an adaptation for extending human cooperation and coordination. Here I survey five critiques of the adapationist position and offer responses to these critiques. Much of the debate can be resolved by clearly defining important but ambiguous terms in the debate, such as religion, adaptation, adaptive, and trait, as well as clarifying several misunderstandings of evolutionary processes. I argue that adaptationist analyses must focus on the functional effects of the religious system, the coalescence of independent parts that constitute the fabric of religion.