St. Augustine

North African bishop who wrote Confessions, City of God, and On Christian Doctrine — the most influential theologian in Western Christianity — who converted from Manicheanism through Platonism to Christianity, synthesized Platonic philosophy with Christian theology, and formulated the doctrines of original sin and predestination.

Created Western Christian theology as an intellectual system — Augustine's synthesis of Platonic philosophy with Pauline Christianity (time, memory, the will, original sin, divine grace) provided the theological framework that Catholic and Protestant Christianity have argued within for 1600 years.