"The Apostle Paul could not mean to contradict himself by saying, 'The doers of the law will be justified' (Rm 2:13), as if their justification came through their works, and not through grace; since he declares that a man is justified freely by His grace without the works of the law (Rm 3:24, 28), intending by the term 'freely' nothing else than that works do not precede justification. For in another passage he expressly says, 'If it is by grace, it is no longer on the basis of works; otherwise grace would no longer be grace.' (Rm 11:6). But the statement that 'the doers of the law will be justified' (Rm 2:13) must be so understood, as that we may know that they are not otherwise doers of the law, unless they be justified, so that justification does not subsequently accrue to them as doers of the law, but justification precedes them as doers of the law. For what else does the phrase 'being justified' signify than being made righteous - by Him, of course, who justifies the ungodly man that he might become a godly one instead?

 

"If we were to express a certain fact by saying, 'The men will be liberated,' the phrase would of course be understood as asserting that the liberation would accrue to those who were men already; but if we were to say, The men will be created, we should certainly not be understood as asserting that the creation would happen to those who were already in existence, but that they became men by the creation itself. If in like manner it would be said that the doers of the law will be honored, we should only interpret the statement correctly if we supposed that the honor was to accrue to those who were already doers of the law. But when the claim is, 'The doers of the law shall be justified,' what else does it mean than that the just shall be justified? For of course the doers of the law are just persons. Thus it amounts to the same thing as if it were said, The doers of the law shall be created - not those who were so already, but that they may become such - in order that the Jews who were hearers of the law might hereby understand that they wanted the grace of the one who justifies, in order to be able to become its doers also. Or else the term 'They shall be justified' is used in the sense of, they shall be deemed, or reckoned as just, as it is predicated of a certain man in the Gospel, 'But he, desiring to justify himself' (Lk 10:29); meaning that he wished to be considered and accounted just."

 

"In like manner, we attach one meaning to the statement, 'God sanctifies His saints,' and another to the words, 'Sanctified (Hallowed) be Thy name' (Mt 6:9); for in the former case we suppose the words to mean that He makes those to be saints who were not saints before, and in the latter, that the prayer would have that which is always holy in itself be also regarded as holy by men, - in a word, be feared with a hallowed awe." 

 

Augustine, On the Spirit and the Letter, 1.45