What does it mean to be a good Christian citizen today? This book examines Augustine\'s ethics of citizenship through an analysis of his theological writings, letters, and sermons. Introducing the Augustinian Necessitas Caritatis (Duty of Love), it identifies the non-negotiable elements of Christian civic identity and clarifies the responsibilities of believers in pluralistic societies. With a focus on Christian European identity, it also discusses the critical role of Augustinian citizens in shaping the future of a truly pluralistic Europe. Written by Pawel Marek Szymanowski, this study was researched and defended as his doctoral dissertation at the Accademia Alfonsiana in Rome.