Roughly, religion is a community's costly and hard-to-fake commitment to a counterfactual and counterintuitive world of supernatural agents who maste… - Scott Atran

The more one accepts what is materially false to be really true, and the more one spends material resources in displays of such acceptance, the more others consider one's faith deep and one's commitment sincere.

Supernatural agents are critical components of all religions but not of all ideologies. They are, in part, by-products of a naturally selected cognitive mechanism for detecting agents-such as predators, protectors, and prey-and for dealing rapidly and economically with stimulus situations involving people and animals. This innate releasing mechanism is trip-wired to attribute agency to virtually any action that mimics the stimulus conditions of natural agents: faces on clouds, voices in the wind, shadow figures, the intentions of cars or computers, and so on. Among natural agents, predators such as snakes are as likely to be candidates for deification as are protectors, such as parent-figures.

Religious ritual invariably offers a sacrificial display of commitment to supernatural agents that is materially costly and emotionally convincing. Such ritual conveys willingness to cooperate with a community of believers by signaling an open-ended promise to help others whenever there is true need. These expensive and sincere displays underscore belief that the gods are always vigilant and will never allow society to suffer those who cheat on their promises. Such a deep devotion to the in-group habitually generates intolerance toward out-groups. This, in turn, leads to constant rivalry and unending development of new and syncretic religious forms.