North African theologian and church leader; d. 430. His father seems to have been a pagan; his mother, Monica, was a devout Christian. While a student, Augustine took a concubine to whom he remained faithful for fifteen years; their son, Adeodatus, was born around 373. Soon after, Augustine, beginning an intense search for truth, dismissed Christianity as an unrefined religion and joined the Manichees, a Gnostic-like sect. The Manichaean worldview quickly disillusioned him, but in 384 he moved to Milan to become a professor.

Around the same time he met a group of Christian philosophers that included Ambrose, a church leader. In 386, Augustine underwent a profound conversion; he renounced his career and his concubine, and after Monica's death, he returned to Africa. While visiting the city of Hippo in 391, the church, against his will, ordained him as an elder. When its bishop died, Augustine became his successor. As a leader, Augustine argued that sexuality is not inherently evil, yet at the same time he never escaped the concept (common to Manichaeism and Platonism) that sexual relations pull the soul downward.

After the Goths sacked Rome in 410, many non-Christians claimed the "Eternal City" had fallen because the Romans had forsaken the ancient gods. In City of God, Augustine countered their claims, demonstrating that every human regime—every ""City of Mankind""—is bound to fall. Christian worship (especially the Lord's Supper) points us toward the "City of God," the only eternal realm. See also Gnosticism.