I answer that, As stated above (A. 1), there is a twofold element in the Law of the Gospel. There is the chief element, viz. the grace of the Holy Ghost bestowed inwardly. And as to this, the New Law justifies. Hence Augustine says (De Spir. et Lit. xvii): "There," i.e. in the Old Testament, "the Law was set forth in an outward fashion, that the ungodly might be afraid"; "here," i.e. in the New Testament, "it is given in an inward manner, that they may be justified." The other element of the Evangelical Law is secondary: namely, the teachings of faith, and those commandments which direct human affections and human actions. And as to this, the New Law does not justify. Hence the Apostle says (2 Cor. 3:6) "The letter killeth, but the spirit quickeneth": and Augustine explains this (De Spir. et Lit. xiv, xvii) by saying that the letter denotes any writing external to man, even that of the moral precepts such as are contained in the Gospel. Wherefore the letter, even of the Gospel would kill, unless there were the inward presence of the healing grace of faith.
Reply Obj. 1: This argument holds true of the New Law, not as to its principal, but as to its secondary element: i.e. as to the dogmas and precepts outwardly put before man either in words or in writing.
Reply Obj. 2: Although the grace of the New Testament helps man to avoid sin, yet it does not so confirm man in good that he cannot sin: for this belongs to the state of glory. Hence if a man sin after receiving the grace of the New Testament, he deserves greater punishment, as being ungrateful for greater benefits, and as not using the help given to him. And this is why the New Law is not said to "work wrath": because as far as it is concerned it gives man sufficient help to avoid sin.
Reply Obj. 3: The same God gave both the New and the Old Law, but in different ways. For He gave the Old Law written on tables of stone: whereas He gave the New Law written "in the fleshly tables of the heart," as the Apostle expresses it (2 Cor. 3:3). Wherefore, as Augustine says (De Spir. et Lit. xviii), "the Apostle calls this letter which is written outside man, a ministration of death and a ministration of condemnation: whereas he calls the other letter, i.e. the Law of the New Testament, the ministration of the spirit and the ministration of justice: because through the gift of the Spirit we work justice, and are delivered from the condemnation due to transgression." ________________________
THIRD ARTICLE [I-II, Q. 106, Art. 3]
Whether the New Law Should Have Been Given from the Beginning of the
World?
Objection 1: It would seem that the New Law should have been given from the beginning of the world. "For there is no respect of persons with God" (Rom. 2:11). But "all" men "have sinned and do need the glory of God" (Rom. 3:23). Therefore the Law of the Gospel should have been given from the beginning of the world, in order that it might bring succor to all.
Obj. 2: Further, as men dwell in various places, so do they live in various times. But God, "Who will have all men to be saved" (1 Tim. 2:4), commanded the Gospel to be preached in all places, as may be seen in the last chapters of Matthew and Mark. Therefore the Law of the Gospel should have been at hand for all times, so as to be given from the beginning of the world.
Obj. 3: Further, man needs to save his soul, which is for all eternity, more than to save his body, which is a temporal matter. But God provided man from the beginning of the world with things that are necessary for the health of his body, by subjecting to his power whatever was created for the sake of man (Gen. 1:26-29). Therefore the New Law also, which is very necessary for the health of the soul, should have been given to man from the beginning of the world.
On the contrary, The Apostle says (1 Cor. 15:46): "That was not first which is spiritual, but that which is natural." But the New Law is highly spiritual. Therefore it was not fitting for it to be given from the beginning of the world.