Across religious belief systems, some supernatural agents are nearly always granted privileged epistemic access into the self's thoughts. In addition, the ethnographic literature supports the claim that, across cultures, supernatural agents are envisioned as incapable of being deceived through overt behaviors; preoccupied with behavior in the moral domain; punitive agents who cause general misfortune to those who transgress and; committed to an implicit social contract with believers that is dependent on the rules of reciprocal altruism. The present article examines the (...) possibility that these factors comprise a developmentally based, adaptive information-processing system that increased the net genetic fitness of ancestral human beings living within complex social groups. In particular, the authors argue that fear of supernatural punishment, whether in this life or in the hereafter, encouraged the inhibition of selfish actions that were associated with "real" punishment by actual group members. (shrink)