What is the main conflict in Augustine of Hippo: A Biography, by Peter Brown by Peter Brown?

Once installed as a professional cleric, Augustine was faced with a kind of challenge from pagans that readers of North America will find extremely foreign. Rome was in the process of becoming Christian during this time. The religion was well known enough in parts of the region to have made 'headway' in terms of growth. At the same time, the predecessors of Christ and his new strange brand of Judaism, had held sway for a great many centuries, in some cases for millenia. This came to involve very staunch political maneuvers within the district he served. The closest thing to this in North America in most cases nowadays would be the Catholic jostling with the Protestants over the region.