St. Augustine
When Christianity became the predominant creed of the empire under Constantine (converted 312) and the sole official religion under Theodosius (379–395), political philosophy changed profoundly. St. Augustine’s City of God (413–426/427), written when the empire was under attack by Germanic tribes, sums up and defines a new division between church and state and a conflict between “matter” and “spirit” resulting from original sin and the Fall of Man from the Garden of Eden.
St. Augustine, whose Confessiones (397) is a record of a new sort of introspection, combined a Classical and Hebraic dualism. From the Stoics and Virgil he inherited an austere sense of duty, from Plato and the Neoplatonists a contempt for the illusions of appetite, and from the Pauline and patristic interpretation of Christianity a sense of the conflict between Light and Darkness that reflects Zoroastrian and Manichaean doctrines emanating from Iran. In this context worldly interests and government itself are dwarfed by the importance of attaining salvation and of escaping from an astrologically determined fate and from the demons who embody the darkness. Life becomes illuminated for the elect minority by the prospect of eternal salvation or, for those without grace, shrivels under the glare of eternal fires.
St. Augustine regarded salvation as predestinate and the cosmic process as designed to “gather” an elect to fill the places of the fallen angels and so “preserve and perhaps augment the number of the heavenly inhabitants.” The role of government and indeed of society itself becomes subordinated to a “secular arm,” part of an earthly city, as opposed to the “City of God.” The function of government is to keep order in a world intrinsically evil.
Since Christianity had long played the main role in defense of the veneer of a precarious urban civilization in antiquity, this claim is not surprising. Constantine was a soldier putting to rights a breakdown in government, which nevertheless would continue in the West until the abdication of the last Western emperor in 476, though in the East the empire would carry on with great wealth and power, centred on the new capital of Constantinople (see Byzantine Empire).
St. Augustine thus no longer assumed, as did Plato and Aristotle, that a harmonious and self-sufficient good life could be achieved within a properly organized city-state; he projected his political philosophy into a cosmic and lurid drama working out to a predestinate end. The normal interests and amenities of life became insignificant or disgusting, and the Christian church alone exercised a spiritual authority that could sanction government. This outlook, reinforced by other patristic literature, would long dominate medieval thought, for with the decline of civilization in the West the church became more completely the repository of learning and of the remnants of the old civilized life.