St. Augustine of Hipp is a Doctor of the Church, a Western Father of the Church, and whose conversion to Christianity is called one of the most important events in the history of the Church. Augustine was born in Tagaste, in northern Africa, the son of Patricius, a pagan Roman official. His mother, St. Monica, was a Christian, and she raised Augustine in the faith. In 370, he went to Carthage to study law, turning instead to literary interests. He also took a mistress, who bore him a son, Adeodatus. In 373, Augustine and his friend Honoratus became members of the Manichaean heretical sect. At the same time his brilliance was manifesting itself, as he won poetic tournaments and became known in the philosophical world. It took nine years for Augustine to free himself from his former life and Manichaeism. In 383, he went to Italy, having to depart in secret because of St. Monica’s opposition.

Augustine planned to teach in Rome but instead went to Milan, where he met St. Ambrose. With Ambrose’s influence, Augustine determined to live a life a celibacy, study, and prayer. St. Monica joined her son in Milan, where St. Alipius, Augustine’s lifelong friend, also resided. With his mother, son, and friends, Augustine retired to a villa to begin his study of the Scriptures and ancient philosophers.

On Easter Sundy of 387, Augustine was baptized by St. Ambrose. Planning to return to Tagaste, the company went to Ostia, to board a ship. St. Monica died in Ostia, and Augustine, filled with grief, stayed in Italy for a time, writing and praying. In Tagaste, in 388, he sold his goods, distributed money to the poor, and began a life of penance. His fame soon spread to surrounding towns, and in 391, while visiting Hippo Regius, he was seized by a crowd, and carried to the aged bishop, Valerius, and ordained a priest. Four years later, he was appointed coadjutor to the diocese of Hippo. Augustine was forty-two at the time, succeeding to the see around 395. He occupied the see of Hippo for thirty-four years. The years were filled with constant writing and the need to confront numerous crises caused by the heresies of the time: the Donatists, Pelagians and Semi-Pelagians, and the Manichaeans. For his defense of Church doctrine concerning grace against the Pelagians, he is known also as the Doctor of Grace. He made his episcopal residence a monastery, sending out priests to make new foundations and providing well-trained bishops for dioceses. His major apostolate was in preaching and writing. He attended councils in 398, 401, 407, 416, 418, and 419.

In 426, Augustine, age seventy-two, named Heraclius his auxiliary and successor. He sought rest but faced political and military turmoil and the Arian heresy. Bishops and political leaders flocked to Hippo for refuge from the Arian heretics and the Vandal invasion of the region. Hippo was itself put under an eighteen-month siege by the forces of the Vandals. Augustine spent three months in prayerful decline during the siege, dying on August 30, 430.

Augustine was a voluminous writer, authoring 113 books, 218 letters, and some five hundred sermons. His literary output covers the entire sphere of human thought and ranges from the psychological complexity of the Confessions, to the political insights of the city of God, to the stridently polemical. He was especially concerned with the combating o the three great heresies of the time: Pelagianism, Donatism, and Manichaeism. His writings, however, are distinguished by their eloquence, superb use of the Latin language, and the degree, born out of the necessity of the crisis of the moment, which he examined and elucidated vital points of Christianity.

Augustine’s enormous contributions to Christian theology would be preeminent until the 1200s and surrendered their virtual monopoly on theological thought only to another towering figure, St. Thomas Aquinas. His extensive system, including such doctrines as grace and original sin, and the Fall, served as the impetus for a host of theologians and interpreters, the so-called Augustinians or adherents of Augustinianism.

In 700, the remains of St. Augustine were placed in a church of San Pietro in Ciel d’Oro, in Pavia, Italy. He is the patron of the Augustinians, theologians, and the city of Carthage.

To be declared a Doctor of the Church, you have to meet three basic requirements:

1. First, you must have lived a life of exemplary holiness, or insignis vitae sanctitas (outstanding sanctity). In short, you have to be a saint.
   

2. Second, to be a Doctor of the Church you must have deepened the whole Church's understanding of the Catholic Faith with emins doctrina (eminent teaching). Which is to say, sanctity isn't enough. There are thousands of saints, but only 37 Doctors of the Church. To be a Doctor one must do more than just live the Faith. Rather, one must significantly and profoundly contribute to our understanding of Divine Revelation, helping us to know more deeply some truth about God and His actions in the World.
   

3. And third, a pope must officially declare you a Doctor. That being said, as the Church understands it, when a pope declares someone a Doctor of the Church, he's not so much making someone a Doctor as he is recognizing what the Holy Spirit has already done - that He has conferred the charism of Doctor upon them.