The Church Cannot Be an Elite in the World
“Pelagianism was an onslaught on the languid, second-rate Christianity which blurred the line between a conventional Christian and the ordinary, pagan Roman. ‘God wished his people to be holy and free from all injustice an iniquity. He wished it to be so, so devout, so pure, so immaculate, so innocent, that the heathen might find nothing to revile in it’; a Christian whose conduct is indistinguishable from a pagan’s is the beginning of blasphemy. … For Pelagius and his followers Christianity is a demand for moral ardor and unceasing struggle with inertia: ‘it is no better to do nothing than to do wickedly.’ …
Augustine was quick to see the affinities [between Pelagianism and Donatism], and he diagnosed the roots of the two maladies in the same fundamental error: the impatient, peremptory anticipation here and now, before the time, of the Church’s eschatological purity. … His answer to both Donatist and Pelagian perfectionism was the same. It was the answer he had learnt from the dissident Donatist theologian Tyconius: the Church here on earth is a mixed body in which the holy rub shoulders with the wicked. The wheat and the tares, as Augustine was always reminding the Donatists, must be allowed to co-exist until the harvest. The Church cannot be an elite in the world; it is necessarily holy and worldly at the same time, to be purified only at the end. The ecclesiology Augustine deployed against Donatism had been an attack on one brand of perfectionism. Pelagian perfectionism raised new problems and demanded new theological labors; but the direction of Augustine’s answer to Pelagius was already settled. It had to be a vindication of Christian mediocrity.”
[R. A. Markus, The End of Ancient Christianity, 52–3]