"This project focuses on the intersection of Roman Imperial politics and Christian theology in the 4th century AD. It contends that during this period, Christian theology became the principal realm in which political structure and theory were debated. Chapters 1-2 argue that the Emperor Constantine possessed a consistent theological viewpoint centered on the justification of his legitimacy in religious terms, as a charismatic "Man of God" appointed by a monarchical deity to supreme rule. This theology in later stages was developed in dialogue with that of Eusebius of Caesarea, also profiled in Chapter 2, which posited a chain of monarchical powers extending from heaven to Earth. Chapters 3-4 provides a narrative of the reign of Constantine's son Constantius II, whose interventions focused on the urgent need to repair the failing Constantinian Settlement and justify his rule against dynastic and episcopal rivals. The final two chapters focus on the development, by an alliance of bishops including Lucifer of Cagliari and Hilary of Poitiers, of a consensus "Nicene" political theology centered on the assertion of equality among divine and human persons and a theory of legitimacy whereby bishops, not Emperors, represented the divine in human society. As described in the Epilogue, this conflict ultimately gave way to a more collaborative settlement under Theodosius I, requiring the Emperor to construct his legitimacy not as a privileged agent within a fixed cosmic order, but as a holder of essentially temporary, "secular" power within the structures and rituals of the Christian Church"--