No doubt the spiritual and moral standards for the Christian life had relaxed quite a bit since the days of persecution, when even the hint of Christian faith could cost a person his or her life; no doubt some restored tension, some call for a renewal of holiness, was surely needed. But Pelagianism, like many zealous movements of moral and spiritual reform, writes a recipe for profound anxiety. Its original word of encouragement (You can do it!) immediately yields to the self-doubting question: “But am I doing it?” It makes a rigorous asceticism the only true Christian life — as [Peter] Brown points out, “Pelagius wanted every Christian to be a monk” — and condemns even the most determined ascetic to constant self-scrutiny, a kind of self-scrutiny that can never yield a clear acquittal. You might have missed something; and in any case you could sin in the next five minutes and watch your whole house of cards crash down.

By contrast, Augustine’s emphasis on the universal depravity of human nature — seen by so many then and now as an insult to human dignity — is curiously liberating. I once heard a preacher encourage his listeners to begin a prayer with the following words: “Lord, I am the failure that you always knew I would be.” It is the true Augustinian note. Pelagianism is a creed for heroes; but Augustine’s emphasis on original sin, and the consequent absolute dependence of every one of us on the grace of God, gives hope to the waverer, the backslider, the slacker, the putz, the schlemiel. We’re all in the same boat as Mister Holier-than-Thou over there, saved only by the grace that comes to us in Holy Baptism. Peter Brown once more: “Paradoxically, therefore, it is Augustine, with his harsh emphasis on baptism as the only way to salvation, who appears as the advocate of moral tolerance: for within the exclusive fold of the Catholic church he could find room for a whole spectrum of human failings.”

— from my Original Sin: A Cultural History; quote prompted by this essay by Elizabeth Bruenig.