With the 500th anniversary of the Protestant Reformation being celebrated especially on this day (Oct 31st), it's always important to keep in mind that Luther was not the first to draw attention to the biblical doctrine of salvation by grace alone through faith alone. St. Augustine was one such figure who stridently defended the doctrines of scripture and the attack on the gospel found in the writings of Pelagius.
The history of the monk Pelagius is a compelling read and illustrates how he frequently crossed heads with the early church’s St. Jerome and St. Augustine. Augustine spoke out against the merited grace doctrine of Pelagius in a series of letters and doctrinal treatises. Historian Rebecca Harden Weaver describes it thus:
“The issue for him was the utterly gratuitous character of grace. Any connection between the divine conferral of grace and human distinctions in merit would have the effect of making the former dependent on the latter. Grace would be a reward. Such an arrangement was totally unacceptable to Augustine. Instead, he argued that God had created human nature as good; yet in Adam all participated in sin and, as a result, deserve damnation. The grace of God, however, rescues some from their just deserts and bestows on them eternal life.” (Rebecca Harden Weaver, Divine Grace and Human Agency: A Study of the Semi-Pelagian Controversy (Macon, GA: Mercer University Press, 1996), 5)