The relationship between religion and morality has long been hotly debated. Does religion make us more moral? Is it necessary for morality? Do moral inclinations emerge independently of religious intuitions? These debates, which nowadays rumble on in scientific journals as well as in public life, have frequently been marred by a series of conceptual confusions and limitations. Many scientific investigations have failed to decompose “religion” and “morality” into theoretically grounded elements; have adopted parochial conceptions of key concepts—in particular, sanitized conceptions of “prosocial” behavior; and have neglected to consider the complex interplay between cognition and culture. We argue that to make progress, the categories “religion” and “morality” must be fractionated into a set of biologically and psychologically cogent traits, revealing the cognitive foundations that shape and constrain relevant cultural variants. We adopt this fractionating strategy, setting out an encompassing evolutionary framework within which to situate and evaluate relevant evidence. Our goals are twofold: to produce a detailed picture of the current state of the field, and to provide a road map for future research on the relationship between religion and morality.