The past few years have been instructive for observers of religious terrorism. Events have conspired to reveal ever more of its grim visage, inner logic, and awful potential. Religious terrorism has been exhaustively analyzed as a security problem, a military problem, an economic problem, a political problem, and more. But it is also an intellectual problem, one with particular implications for the study of law, culture, and history. This Essay examines the intellectual assumptions of religious terrorism, and it does so from three distinct perspectives: the theory of religion and American constitutional law (Part I); the common law (Part II); and cultural and institutional history (Parts III and IV).