Augustine is not only known as the thinker who presented Christianity to the pagan Roman society in a manner which made it intelligible, respectable, and appealing to many in that culture, but he also worked to preserve the harmony inside the infant church as it faced some of its first major debates.
Augustine was also responsible for creating some unity within the church, as rival factions and critics, threatened to splinter the church apart. Two main rivals to Augustinian Catholic Christianity were the Donatists and the Pelagians. The Pelagians were group that followed the teachings of Pelagius, a British ascetic, who believed that salvation was given through human will and effort. Pelagius believed that Adam’s ‘Original Sin’ did not taint all of mankind. He believed that humans had a good deal of freedom and autonomy. Augustine had a different belief. Augustine believed in Paul’s ideas regarding Original Sin and salvation. He believed that everyone is born with Adam’s sin, and thus deserve eternal damnation. But God, being forgiving, allows people to be saved. He believes that salvation is a gift from God. Thus, mankind has no role in determining his eternal fate. This idea became known as ‘predestination’. Augustine was firm in his beliefs. He believed that humans have free will, but it had no impact on whether they are saved. Ultimately, the teachings of Pelagius were rejected by the Council of Carthage in 418 A.D. Interestingly, the Catholic Church never adopted Augustine’s interpretation on salvation, and believed instead that salvation was a combination of faith and good works. The debate continued. However, later Protestants, like John Calvin, revived Augustine’s concept of predestination. The fact that Augustine silenced a rival and influenced Protestantism showed his great impact. No doubt, the Romans of his time took notice.
The Donatists were another group that threatened to splinter Christianity into separate sects. The Donatists, named after a Christian man named Donatus, argued that a member of the clergy that had either renounced their faith in a time of persecution, or had sinned in other ways, could not be a member of the church. Thus, they could not give out the sacraments, like the eucharist. They were worried that Christians taking part in this religious rite were not getting the benefits of it, as it was done in an improper manner. So, in essence, the question was, can a clergyman who has fallen from the church in some manner, give the sacraments? Augustine argued they still could. In fact, the debates between the Donatists and Augustine were legendary. Augustine did not relent on any of the issues. He argued persuasively and with reason. His debate with the Donatists forever changed the identity and government of the Church. The fact that he debated publicly the merits of Christianity could not help but be influential to the scholars of Rome.
Augustine's contributions to these discussions worked to sharpen the concept of "grace" - the notion that God's love for human beings is unearned, unmerited, and undeserved. God gives good things to people, not because they deserve it, but because He is generous.
The concept of "predestination" is both complex and misleading. No man can earn or choose salvation from God: man is passive in this process, and God is actively giving the salvation. But once God has given the salvation, man can become active, and choose to reject the free gift. Involved here is a fine distinction between those instances in which the human will is free, and those in which is determined. The discussions continue to this day about the exact meaning of the word "predestination."