This chapter explores the profound continuity between ancient Greco-Roman conceptions of human flourishing, rooted in culture and a holistic view of nature, and medieval Christian culture, contrary to narratives of rupture that portray the Middle Ages as a Dark Age. Drawing on István Bibó’s historical analysis of European political development, it argues that Christianity uniquely humanized power through the separation, yet still effective mutual oversight of Church and state, fostering moral restraint, mutual obligations, and institutional checks on tyranny. This process, supported by Augustine’s synthesis of Roman rationality and Christian pacifism, gave rise to ideals of the virtuous king, citizen, and knight, and prepared the way for the birth of a lay intelligentsia through the order of secular scribes and made possible the unfolding of a refined urban civility The chapter further contends that the medieval religious worldview was not overcome by the new discourses of humanism. Instead, it laid down the essential groundwork for Renaissance Christian humanism. Examining medieval forms of art, including cathedrals, guilds, universities, and court society, the chapter demonstrates how religious devotion shaped communal cooperation, self-government, scholastic debate, and refined manners. Influenced by Rémi Brague’s emphasis on cultural transmission and Norbert Elias’s account of the civilizing process, the analysis reveals medieval Europe as a dynamic continuum bridging antiquity and early modernity, where faith both moralized power and civilized the whole realm of political interactions.