In Alister McGrath’s Historical Theology there is an entire section on the Donatist vs. Augustine controversy. Let me explain the issues that caused this controversy in the early church. One of the great dilemmas for the early church was how to deal with those Christians who had lapsed during persecution, that is, those who gave in and bought the libellus or who just simply offered sacrifices to idols in order to keep their lives. The Donatists believed that the Church was a body of saints within which sinners had no place. They argued that the “traditores” (lapsed) had to be excluded from the Church. This began the Donatist Controversy into which Augustine poured so much effort. Augustine responded by saying that the church was a mixed body with both sinners and saints. This initial concept of a mixed Church would be incorporated centuries later by the Westminster Divines who brought about the distinction between the Visible and Invisible Church.
According to Augustine, the Church was no place for saints alone and was not established by saints alone. It was made by all who partook of the Sacraments. Augustine’s idea of the Lord’ Supper led to even more division with the Donatists who believed in “ex opere operantis” which teaches that the validity of the Sacraments are based on the integrity of those who administer it. Whereas for Augustine “ex opere operato” was a more accurate approach to the Sacraments since the validity of bread and wine does not depend on the one administering them, but depends on the One who bestows the grace to the elements. This reveals a stark contrast between both views spoused in this controversy. The Donatists in the tradition of Pelagianism, believed that Christianity is a religion of autonomy where man in and of himself can accomplish his salvation outside of any intervention by God. Augustine, of course, believed that man could not do anything without God’s grace (John 15:5).
My commitment to Augustinianism is the commitment of the Reformers who stood entirely with the necessity of grace in all of human existence, in life and in death.