Reply Obj. 3: As stated above (Q. 106, AA. 1, 2), the New Law is called the law of faith, in so far as its pre-eminence is derived from that very grace which is given inwardly to believers, and for this reason is called the grace of faith. Nevertheless it consists secondarily in certain deeds, moral and sacramental: but the New Law does not consist chiefly in these latter things, as did the Old Law. As to those under the Old Testament who through faith were acceptable to God, in this respect they belonged to the New Testament: for they were not justified except through faith in Christ, Who is the Author of the New Testament. Hence of Moses the Apostle says (Heb. 11:26) that he esteemed "the reproach of Christ greater riches than the treasure of the Egyptians." ________________________
SECOND ARTICLE [I-II, Q. 107, Art. 2]
Whether the New Law Fulfils the Old?
Objection 1: It would seem that the New Law does not fulfil the Old. Because to fulfil and to void are contrary. But the New Law voids or excludes the observances of the Old Law: for the Apostle says (Gal. 5:2): "If you be circumcised, Christ shall profit you nothing." Therefore the New Law is not a fulfilment of the Old.
Obj. 2: Further, one contrary is not the fulfilment of another. But Our Lord propounded in the New Law precepts that were contrary to precepts of the Old Law. For we read (Matt. 5:27-32): "You have heard that it was said to them of old: . . . 'Whosoever shall put away his wife, let him give her a bill of divorce. But I say to you that whosoever shall put away his wife . . . maketh her to commit adultery.'" Furthermore, the same evidently applies to the prohibition against swearing, against retaliation, and against hating one's enemies. In like manner Our Lord seems to have done away with the precepts of the Old Law relating to the different kinds of foods (Matt. 15:11): "Not that which goeth into the mouth defileth the man: but what cometh out of the mouth, this defileth a man." Therefore the New Law is not a fulfilment of the Old.
Obj. 3: Further, whoever acts against a law does not fulfil the law. But Christ in certain cases acted against the Law. For He touched the leper (Matt. 8:3), which was contrary to the Law. Likewise He seems to have frequently broken the sabbath; since the Jews used to say of Him (John 9:16): "This man is not of God, who keepeth not the sabbath." Therefore Christ did not fulfil the Law: and so the New Law given by Christ is not a fulfilment of the Old.
Obj. 4: Further, the Old Law contained precepts, moral, ceremonial, and judicial, as stated above (Q. 99, A. 4). But Our Lord (Matt. 5) fulfilled the Law in some respects, but without mentioning the judicial and ceremonial precepts. Therefore it seems that the New Law is not a complete fulfilment of the Old.
On the contrary, Our Lord said (Matt. 5:17): "I am not come to destroy, but to fulfil": and went on to say (Matt. 5:18): "One jot or one tittle shall not pass of the Law till all be fulfilled."
I answer that, As stated above (A. 1), the New Law is compared to the Old as the perfect to the imperfect. Now everything perfect fulfils that which is lacking in the imperfect. And accordingly the New Law fulfils the Old by supplying that which was lacking in the Old Law.
Now two things in the Old Law offer themselves to our consideration: viz., the end, and the precepts contained in the Law.