While the Donatist controversy was in full swing, a catastrophe struck the Roman world. In the year 410, Rome, the symbolic capitol of an empire that had dominated the known world for hundreds of years, was looted and burned by the armies of the Visigoths, northern European barbarian tribes. Many people throughout the empire believed that the fall of Rome marked the end of civilization as they knew it. In response, Augustine began writing his greatest masterpiece, The City of God Against the Pagans, which he worked on for 15 years. In The City of God, Augustine places the heavenly and eternal Jerusalem, the true home of all Christians, against the transitory worldly power represented by Rome, and in doing so, he articulates an entirely new Christian world view.
About the time of the fall of Rome, a movement called Pelagianism began in the church, calling for a fundamental renewal of spiritual and physical discipline. Its founder, a British monk named Pelagius, had read Augustine's plea to God in the Confessions, "Grant what you command and command what you will" (10.29). Pelagius was horrified by the apparent human helplessness that Augustine's statement seemed to imply. If human beings were incapable of being good without God's assistance, then what use was human free will? Pelagius argued that human beings could choose to achieve moral perfection through sheer force of will — and not only that they could, but that they must. Augustine, on the other hand, argued that no human being could expect to achieve anything like moral perfection; human will was irrevocably tainted by original sin. Christians could and should strive toward goodness, but they must also recognize their fallen state and their dependence upon the grace of God.
