In the fourth century, another revival movement arose, embraced by Augustine, who was Bishop of Hippo. The problem with the Donatists, Augustine argued, is that they are too static. They try to seal off an ark to ride out the storm, but they end up sealing themselves in. They cut themselves off from new circumstances and growth.
Augustine, as his magisterial biographer Peter Brown puts it, “was deeply preoccupied by the idea of the basic unity of the human race.” He reacted against any effort to divide people between those within the church and those permanently outside.
He wanted the church to go on offense and swallow the world. This would involve swallowing impurities as well as purities. It would mean putting to use those who are imperfect. This was the price to be paid if you wanted an active church coexisting with sinners, disciplining and rebuking them.