This chapter explores how the institutions of early agrarian states sought to align deeply ingrained Pleistocene cognitive tendencies with the moral and behavioral demands of complex societies. Even as religions became doctrinal and hierarchical, humans retained a shamanic impulse to seek guidance from spiritual intermediaries through altered states—pain, fasting, or trance—reflecting continuity with forager traditions. State religions adapted these tendencies to reinforce social order, using rituals, architecture, and constant reminders of watchful deities to activate evolved concerns for reputation and reciprocity. Experiments and cross-cultural studies suggest that belief in moralizing, punitive gods enhanced cooperation and altruism among strangers, enabling large-scale societies to function cohesively. The chapter concludes by examining monotheism as an institutional ideal that often fails to overcome the human tendency toward polytheism. Even in “monotheistic” faiths, people persistently populate their worlds with multiple spirits, saints, and supernatural agents, reflecting the enduring architecture of our Pleistocene minds.