After he fully put his faith in Christ, Augustine immediately abandoned his secular career. He decided to move back to Africa, but en route, both his mother and son died. The grief-stricken Augustine pressed on, intending to found a monastery. He went to visit a friend in Hippo hoping to recruit him to this endeavor. While there, Valerius, the bishop of Hippo, stirred up the congregation, and they pressed him into staying and serving their church. Against his will, Augustine was ordained a priest. Within a few years Valerius died, leaving Augustine the bishop of Hippo.
Soon he was consumed with the pastoral duties of the church. While he wouldn’t live the quiet, reflective life of a monk, Augustine continued his studies and writing. During this period, he wrote the works that would most influence Western Christianity.
Augustine confronted many heresies in his time, among the most notable was his arguments against Pelagianism.
Pelagius was a British monk who argued that man was capable of living a sinless life and it was theoretically possible for a person to achieve salvation through his or her own works. Augustine knew from personal experience this could not be true.
To fight this heresy, Augustine put forward an argument on original sin, which later came to be known as total depravity. Again, man’s free will was central to his argument. Before the fall, man, through his free will, had the freedom to chose not to sin. When Adam chose to sin, he tarnished human nature and everyone after him inherited this fallen nature. After the fall, man’s will was still free, but the option to choose not to sin disappeared. He had freedom of choice but the only options left were sin. When man is saved, God places His Spirit within him and renews him. Now man is able to choose not to sin, but he is still capable of sin while living in a fallen world. When man arrives in heaven, he still has a free will, but the choice to sin will not be available.
Augustine ardently argued that God alone initiates salvation, not man. Salvation is fully a work of God. God chooses whom to save, and those He has chosen cannot resist His grace.
The Council of Carthage condemned Pelagianism in 418, largely due to Augustine’s writings against it. However, Augustine’s views on original sin, salvation, and predestination did not gain widespread popularity during his lifetime. Later theologians, such as the Reformers Martin Luther and John Calvin, would draw heavily on Augustine’s writings on these topics.
As the bishop of Hippo, Augustine found himself in the center of the greatest theological storms of his time. With the perspective of hindsight, it is clear God had always been preparing him for this role. Through Augustine’s own personal struggles and all of his training in rhetoric, Augustine was uniquely qualified to debate the heresies threatening the church.