Here is an interesting summary of the issue of justification and the doctrine of merit in the Church Fathers and how it played out in the controversy between the Romanists and the Protestants. It is a very solid Protestant summary, but what i found interesting was the way he expressed what he said toward the end of this quote. Take a look.

Augustine, as the great Doctor of Grace, has been singled out, and exhibited with marked prominence, as the advocate of ‘moral, and the opponent of ‘forensic,’ Justification, chiefly because his views, on other subjects, were known to be in accordance with those of the Reformers. For this reason, his authority was supposed to afford a conclusive proof of the novelty of the Protestant doctrine: and, certainly, it would be strange, if it were true, that he who did so much to establish the doctrine of free grace, in opposition to free-will, in the matter of our Sanctification, should have said anything to undermine the doctrine of free grace, in opposition to self-righteousness, in the matter of our Justification. But before we adopt so improbable a conclusion, we must carefully consider the occasion and nature of the controversy in which he was then engaged. It was materially different from the subsequent controversy between Rome and the Reformation. The Pelagians, with whom he was called to contend, admitted the doctrine of Grace in the free remission of sins, while they denied the necessity of efficacious grace for the conversion of the sinner. Their heresy, therefore, did not directly raise the question of a sinner’s Justification in the sight of God, although it involved principles which had an important bearing upon it. They believed, that ‘there is forgiveness with God;’ but they believed also, that man is able of himself ‘to repent and turn to God.’ Augustine defended the doctrine of Grace on the side on which it was then assailed; and, in doing so, he established certain great principles which were sufficient to counteract the tendency, inherent in the Pelagian doctrine, towards a self-righteous scheme of Justification. These two fundamental principles, in particular, were clearly taught by Augustine,–first, that works done before faith are not good, but evil, (splendida peccata); secondly, that works done after faith, although good, as being the fruits of grace in the believer, are so imperfect in themselves, and so defiled by remaining sin, that they need to be sprinkled with the blood of Christ, and can only be accepted through His merits: and these two principles, when combined with his more general doctrine of free, sovereign, efficacious grace, involve the substance of the Protestant doctrine. He affirmed the free grace of God in opposition to the free-will of man, as the spring and fountainhead of a sinner’s whole salvation. That salvation comprehended both his Justification and his Sanctification, the remission of his sins and the renovation of his nature,–and it was ascribed by Augustine, in each of its constituent parts, to the free and unmerited grace of God alone. By establishing this fundamental truth, he laid a firm foundation for the more special doctrine of a free Justification by grace through faith in Christ; and his writings contributed largely to the illustration of that great truth at a later period, when it became the subject of formal controversy between Rome and the Reformers. In this way, and to this extent, Augustine prepared the way for Luther and Calvin, by excluding the merit of man, and exalting the grace of God.

It has been alleged, not only that Augustine knew nothing of a ‘forensic’ Justification by faith, but that he taught the opposite doctrine of a ‘moral’ Justification, by infused or inherent righteousness. This allegation rests mainly on two grounds,–first, the use which he made of the term ‘Merits’ when he spoke of good works; and secondly, the sense in which he used the term ‘Justification,’ when he spoke of the benefit bestowed by the Gospel.

In regard to the first, it has been conclusively proved by most of our great writers in their controversy with the Romish Church, that Augustine, in common with all the Latin Fathers, used the term ‘Merits,’ not to denote legal, or even moral desert, properly so called, but to signify, either simply a means of obtaining some blessing,–or, at the most, an action that is rewardable, not ‘of debt, but of grace.’ It was at a later period, and chiefly through the Scholastic Theology, that the doctrine of Merit, properly so called, was constructed; but, as used by the Fathers, the term had no such offensive meaning as was afterwards attached to it, and denoted merely that by which benefit was obtained. In this general sense, as denoting the obtaining or procuring of something, it was said that we might merit Christ, or merit the Spirit, or merit eternal life; not that we could deserve any one of these inestimable gifts, or that they could ever become due to us in justice,–for this is inconceivable,–but simply that they might thus be procured and enjoyed. In this sense, the verb occurs even in the Protestant Confession of Augsburg; but now, when the meaning of the term has been entirely changed, it is not safe to speak of Merits at all, excepting only the Merits of Christ.

James Buchanan, The Doctrine of Justification: An Outline of its Historyin the Church and of its Exposition from Scripture (1867); Lecture III, History of the Doctrine in the Times of the Fathers and Scholastic Divines (pp. 77-99 Banner of Truth edition).