Saint Augustine was a major figure in bringing Christianity to dominance in the previously pagan Roman Empire. Born in Tagaste, in Numidia, Augustine’s journey to faith was far from straightforward. Converting to Christianity in 386, Augustine had immersed himself first in Manichaeism, then in scepticism, and then in Neo-Platonism. Once a Christian, Augustine became Bishop of Hippo, and a powerful theologian and defender of the faith.

Augustine’s theological career was marked by two campaigns against heresies in particular; first, against the Manichaeism to which he had previously adhered, and second, against Pelagianism.

Manichaeism was a dualist philosophy, according to which there are two transcendent forces responsible for the world, one good and one evil. Its main attraction is that it can more readily explain the mixture of good and evil in the world around us than can the view that we are governed by a single omnipotent and benevolent God. To combat this Persian religion, Augustine affirmed the inherent goodness of God’s Creation. Evil, Augustine argued, does not exist in its own right, but is merely the privation of good, and therefore is not something that was created. All that was created, then is good, so the view that there is a single, good Creator is consistent with the way that the world is.

Pelagianism stressed the ability of man to achieve righteousness by his own strength, and thus played down the need for God’s grace. Pelagius denied original sin, rejecting the idea that each of us inherits guilt for Adam’s sin in Eden, opening up the possibility that by following God’s commands we could be free from sin, rendering Christ’s work on the cross unnecessary. Augustine opposed Pelagius on each of these points; we inherit guilt, according to Augustine, bringing the threat of just punishment upon us, and it is only God’s grace that can liberate us from this condemnation.