Against Two Letters of the Pelagians

Still, indeed, they alike oppose the grace of Christ, they alike make His baptism of no account, they alike dishonour His flesh; but, moreover, they do these things in different ways and for different reasons. For the Manicheans assert that divine assistance is given to the merits of a good nature, but the Pelagians, to the merits of a good will. The former say, God owes this to the labours of His members; the latter say, God owes this to the virtues of His servants. In both cases, therefore, the reward is not imputed according to grace, but according to debt.

The Manicheans contend, with a profane heart, that the washing of regeneration— that is, the water itself— is superfluous, and is of no advantage. But the Pelagians assert that what is said in holy baptism for the putting away of sins is of no avail to infants, as they have no sin; and thus in the baptism of infants, as far as pertains to the remission of sins, the Manicheans destroy the visible element, but the Pelagians destroy even the invisible sacrament. The Manicheans dishonour Christ's flesh by blaspheming the birth from the Virgin; but the Pelagians by making the flesh of those to be redeemed equal to the flesh of the Redeemer.

Since Christ was born, not of course in sinful flesh, but in the likeness of sinful flesh, while the flesh of the rest of mankind is born sinful. The Manicheans, therefore, who absolutely abominate all flesh, take away the manifest truth from the flesh of Christ; but the Pelagians, who maintain that no flesh is born sinful, take away from Christ's flesh its special and proper dignity.