“Therefore I ought first to show that the faith by which we are Christians is the gift of God, if I can do that more thoroughly than I have already done in so many and so large volumes. But I see that I must now reply to those who say that the divine testimonies which I have adduced concerning this matter are of avail for this purpose, to assure us that we have faith itself of ourselves, but that its increase is of God; as if faith were not given to us by Him, but were only increased in us by Him, on the ground of the merit of its having begun from us. Thus there is here no departure from that opinion which Pelagius himself was constrained to condemn in the judgment of the bishops of Palestine, as is testified in the same Proceedings, ‘That the grace of God is given according to our merits,’  if it is not of God’s grace that we begin to believe, but rather that on account of this beginning an addition is made to us of a more full and perfect belief; and so we first give the beginning of our faith to God, that His supplement may also be given to us again, and whatever else we faithfully ask.

“But why do we not in opposition to this, rather hear the words, ‘Who has first given to Him and it shall be recompensed to him again? Since of Him, and through Him, and in Him, are all things.’ Romans 11:35 And from whom, then, is that very beginning of our faith if not from Him? For this is not excepted when other things are spoken of as of Him; but ‘of Him, and through Him, and in Him, are all things.’ But who can say that he who has already begun to believe deserves nothing from Him in whom he has believed? Whence it results that, to him who already deserves, other things are said to be added by a divine retribution, and thus that God’s grace is given according to our merits. And this assertion when put before him, Pelagius himself condemned, that he might not be condemned. Whoever, then, wishes on every side to avoid this condemnable opinion, let him understand that what the apostle says is said with entire truthfulness, ‘Unto you it is given in the behalf of Christ not only to believe in Him, but also to suffer for His sake.’ Philippians 1:29 He shows that both are the gifts of God, because he said that both were given. And he does not say, ‘to believe in Him more fully and perfectly,’ but, ‘to believe in Him.’ Neither does he say that he himself had obtained mercy to be more faithful, but ‘to be faithful,’ 1 Corinthians 7:25 because he knew that he had not first given the beginning of his faith to God, and had its increase given back to him again by Him; but that he had been made faithful by God, who also had made him an apostle. For the beginnings of his faith are recorded, and they are very well known by being read in the church on an occasion calculated to distinguish them:  how, being turned away from the faith which he was destroying, and being vehemently opposed to it, he was suddenly by a more powerful grace converted to it, by the conversion of Him, to whom as One who would do this very thing it was said by the prophet, ‘You will turn and quicken us;’  so that not only from one who refused to believe he was made a willing believer, but, moreover, from being a persecutor, he suffered persecution in defence of that faith which he persecuted. Because it was given him by Christ ‘not only to believe in Him, but also to suffer for His sake.'”

Augustine, On the Predestination of the Saints, Book I, Ch. 3 and 4