Moral relativism is deeply troubling for those who believe that, without a set of moral absolutes, democratic societies will devolve into tyranny or totalitarianism. Engaging directly with this claim, Carlo Invernizzi Accetti traces the roots of contemporary anti-relativist fears to the antimodern rhetoric of the Catholic Church, and then rescues a form of philosophical relativism for modern, pluralist societies, arguing that this standpoint provides the firmest foundation for an allegiance to democracy. In its dual analysis of the relationship between religion and politics and the implications of philosophical relativism for democratic theory, this book makes a far-ranging contribution to contemporary debates over the revival of religion in politics and the conceptual grounds for a commitment to democracy. It conducts the first comprehensive genealogy of anti-relativist discourse and reclaims for English-speaking readers the overlooked work of political theorists such as Hans Kelsen and Norberto Bobbio, who had articulated the bond between philosophical relativism and democracy. By engaging with attempts to replace the religious foundation of democratic values with a neo-Kantian conception of reason, this book also offers a powerful case for relativism as the strongest basis for a civic ethos that integrates different perspectives into democratic politics.