De Doctrina Christiana in the context of "Augustine of Hippo"

Augustine of Hippo (/ɔːˈɡʌstɪn/ aw-GUST-in, US also /ˈɔːɡəstiːn/ AW-gə-steen; Latin: Aurelius Augustinus Hipponensis; 13 November 354 – 28 August 430) was a theologian and philosopher, the bishop of Hippo Regius from Thagaste in Numidia Cirtensis, (present-day Souk Ahras, Algeria). His writings deeply influenced the development of Western philosophy and Western Christianity, and he is viewed as one of the most important Church Fathers of the Latin Church in the Patristic Period. His many important works include The City of God, On Christian Doctrine, and Confessions.

According to his contemporary, Jerome of Stridon, Augustine "established anew the ancient Faith". In his youth he was drawn to the Manichaean faith, and later to the Hellenistic philosophy of Neoplatonism. After his conversion to Christianity and baptism in 386, Augustine developed his own approach to philosophy and theology, accommodating a variety of methods and perspectives. Believing the grace of Christ was indispensable to human freedom, he helped formulate the doctrine of original sin and made significant contributions to the development of just war theory. When the Western Roman Empire began to disintegrate, Augustine imagined the Church as a spiritual City of God, distinct from the material Earthly City. The segment of the Church that adhered to the concept of the Trinity as defined by the Council of Nicaea and the Council of Constantinople closely identified with Augustine's On the Trinity.