“St. Augustine (C.E. 354-430), originally named Aurelius Augustinus, was the Catholic bishop of Hippo in northern Africa. He was a skilled Roman-trained rhetorician, a prolific writer (who produced more than 110 works over a 30-year period), and by wide acclamation, the first Christian philosopher. Writing from a unique background and vantage point as a keen observer of society before the fall of the Roman Empire, Augustine’s views on political and social philosophy constitute an important intellectual bridge between late antiquity and the emerging medieval world. Because of the scope and quantity of his work, many scholars consider him to have been the most influential Western philosopher.
“Although Augustine certainly would not have thought of himself as a political or social philosopher per se, the record of his thoughts on such themes as the nature of human society, justice, the nature and role of the state, the relationship between church and state, just and unjust war, and peace all have played their part in the shaping of Western civilization. There is much in his work that anticipates major themes in the writings of moderns like Machiavelli, Luther, Calvin and, in particular, Hobbes.” (continue article)
—J. Mark Mattox at The Internet Encyclopedia of Philosophy
“The widely influential gnostic religion of late antiquity, founded and spread by the Persian Mani (216-77), taught a radical dualism of good and evil that is metaphysically grounded in coeternal and independent cosmic powers of Light and Darkness. This world was regarded as a mixture of good and evil in which spirit represents Light and matter represents Darkness. Manichaean morality was severely ascetic. Before his conversion to Christianity, Augustine was an adherent of Manichaeism.”
— Philip L. Quinn, The Oxford Companion to Philosophy (Oxford, 1995), 519.
Aurelius Augustinus [more commonly “St. Augustine of Hippo,” often simply “Augustine”] (354-430 C.E.): rhetor, Christian Neoplatonist, North African Bishop, Doctor of the Roman Catholic Church. One of the decisive developments in the western philosophical tradition was the eventually widespread merging of the Greek philosophical tradition and the Judeo-Christian religious and scriptural traditions. Augustine is one of the main figures through and by whom this merging was accomplished. He is, as well, one of the towering figures of medieval philosophy whose authority and thought came to exert a pervasive and enduring influence well into the modern period (e.g. Descartes and especially Malebranche), and even up to the present day, especially among those sympathetic to the religious tradition which he helped to shape (e.g. Plantinga 1992; Adams 1999).
But even for those who do not share this sympathy, there is much in Augustine’s thought that is worthy of serious philosophical attention. Augustine is not only one of the major sources whereby classical philosophy in general and Neoplatonism in particular enter into the mainstream of early and subsequent medieval philosophy, but there are significant contributions of his own that emerge from his modification of that Greco-Roman inheritance, e.g., his subtle accounts of belief and authority, his account of knowledge and illumination, his emphasis upon the importance and centrality of the will, and his focus upon a new way of conceptualizing the phenomena of human history, just to cite a few of the more conspicuous examples.
(Via Stanford Encyclopedia of Philosophy)