This course surveys major topics and perspectives in the study of religion as a social institution. It starts with the classical writings of Troeltsch, Durkheim, Weber, and Geertz, and seeks to answer the following questions using empirical cases drawn from Europe, the United States, Turkey, and India: Why do different societies experience different degrees of secularization? How do church-state relations and secular ideologies vary from one setting to another? Can secularism itself be considered a religion-like formation? What is civil religion? What role does religion play in social movements, and civil societies?