Abstract
This essay argues that economic scarcity, along with mankind’s evolved propensity for reciprocity, are keys to understanding the origins and evolution of Western religion in all its varieties and purposes. Scarcity is religion’s first cause uncaused. Eusocial cooperation and productive efficiency, which are mobilized by religion, are shown to be inherent and rational responses to scarcity. The reformation that began around 1500 CE represents the substitution of efficient secular religions for traditional theological varieties. The balance between traditional and secular religions is determined by cost, benefits, and the structure of economic payoffs.