Ours is a problem of order, cognitive and cultural. Were religion simply chaotic, we would not recognize it as an object of study. In this article, I outline two complementary approaches to religious phenomena; both aim to explain different aspects of order in religion. First, recently-developed cognitive theories of religious phenomena account for some aspects of cultural order in terms of cognitive constraints. Second, complexity theory offers hypotheses about the emergent dynamics of entire religious systems. Before examining these theories themselves, however, I will explain in more detail the problem of order and the place of these theories in explaining it.