St. Augustine was born in 354 in Thagaste in Roman North Africa. At that time, the Church in Africa was riddled with struggles and schisms. While Augustine's father was baptized only shortly before his death, his mother was a devout Catholic Christian. Augustine was raised as a Christian, but was not baptized, following the common practice of the time.

Augustine went to Carthage to study to be a lawyer in 370. He studied there from 372 to 375, when he gave up his pursuit of law and instead established his own schools for rhetoric and grammar in Carthage, which he operated for nine years. Some time during his stay in Carthage he converted to Manicheism, the radical dualistic belief that separates the world into notions of light and dark as good and evil. He remained fascinated with this religion for many years. In 383 Augustine went to Rome to open another school of rhetoric, but was dismayed by the scholars' custom of frequently changing teachers in order to avoid paying their fees.

Throughout his young life, Augustine struggled with his desires for women. He lived with a concubine for many years and fathered an illegitimate son with her. He moved to Milan in 384 and finally dismissed his concubine under the influence of his mother. He became increasingly disillusioned with Manicheism, and set off to pursue a sense of the transcendent when, by chance, he began reading Latin translations of Neoplatonic works.

Inspired by his new reading to believe in a transcendent God, he came under the companionship of Bishop Ambrose of Milan. Ambrose showed him that it was possible and permissible to interpret the Bible allegorically so that it incorporated the Platonic ideals he had been pursuing. Augustine acquired most of his knowledge of theology while studying under Ambrose. He began to reconcile the understanding of a transcendent God that he gained from his Platonic reading with his strong desire for a personal experience with God shown by "the Word became flesh and dwelled among us." He began to learn that God loved the world and that humans should love God and their fellow humans for God's sake as well.

Augustine still struggled to adhere to his faith and live the life demanded of him by God. His sinful past inhibited him. In his famous autobiographical work, the Confessions, Augustine describes the final moment of his conversion when he heard a child's voice speaking to him in a garden saying, "Take and read." Augustine reportedly picked up and read a passage in the letters of St. Paul that called for him to give up all impurities and live for Christ. Through this action, God gave Augustine the grace to completely discard his sinful life and turn wholeheartedly to God.

In 387, Ambrose baptized Augustine, who was almost 33 years old. He was ordained at Hippo in 391 and succeeded the bishop of Hippo in 396.

Augustine was an active and caring bishop who led his people through several wars and cared for the impoverished. He did not hesitate to contract debts for those in need. He was known for his strict teaching and was very influential in the thought on the nature of sin and its effect on the human condition. He wrote the Confessions in 397, a record of his own life struggle to wholeheartedly accept Christianity and live the Christian life. The Confessions is a detailed record and study of human motivation and potential, and the inevitable disappointment that comes from the pursuit of perfection due to human sinfulness. Augustine further developed the thought that sin is inherited by the human race.

Augustine fervently fought several heretics of his time. He is known to have combated the Donatists and Manichees. Furthermore, his writings on the necessity of grace and baptism for salvation led to the condemnation of Pelagius, who believed that salvation could be attained through human decisions and actions. Augustine's thought greatly influenced all following Christian thought and helped to further unify the developing Church.

Augustine's influence on Christianity has spanned the centuries and is still relevant today. He is known as a doctor of the Church-a title given to him and 32 other saints whose writings have had a great impact on Catholic theology or spirituality. St. Augustine died in August 430 during the Vandal's attack on Hippo.