In Matthew 5:17-20 the Lord revealed His true relationship to law. In verse 17, He began by unveiling His purpose toward the law of Moses. He announced:
Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfill.
What did Jesus come to do to the law and the prophets?
The Greek word ("nomos") translated "law" ". . . became the established name for law as decreed by a state and set up as the standard for the administration of justice" (W. E. Vine, An Expository Dictionary of New Testament Words, Vol. II, p. 313). It was the standard word in Jesus' day to describe the Old Testament (cf. Gal. 3:10-18) and, more particularly, the five books of the Old Testament written by Moses, the Pentateuch (cf. Jn. 7:19; 8:5), which included the Ten Commandments (Rom. 7:7). The "prophets" refers, by a figure of speech known as metonymy, to "the writings of the prophets" (Vine, Vol. III, p. 222) and is used to refer to all the Old Testament other than the Pentateuch. Thus, the term "the law and the prophets" describes the entire Old Testament (cf. Matt. 7:12; 11:13; 22:40; Acts 24:14). Therefore, in Matthew 5:17 Christ was discussing His relationship to the Old Testament.
Jesus corrected misgivings concerning His purpose toward the Old Testament by revealing, "I am not come to destroy . . . ." This could not mean He .did not intend to abolish or abrogate the Old Testament, as a law, for the Lord's personally selected ambassador to the Gentiles, the inspired apostle Paul, declared that the Lord did indeed abolish the Old Testament by His death on the cross (Rom. 7:1-6; 2 Cor. 3:6-16; Gal. 3:10-25; 4:21-5:4; Eph. 2:11-16; Col. 2:14-17; Heb. 7:11-19; 8:613; 10:1-9). The term "destroy" means to " . demolish . . . render vain, deprive of success, bring to naught . . ." (J. H. Thayer, A Greek-English Lexicon of the New Testament, p. 334). Had Jesus destroyed the law and the prophets, He would have nullified their purpose, prevented the fulfillment of their types and prophecies and rendered the Old Covenant useless.
The law and the prophets were much more than a system of government. They, being inspired of God (2 Tim. 3:16-17; 2 Pet. 1:20-21), were an important part of the unfolding of God's plan of salvation and are still useful for us today (Rom. 15:4). In the Old Testament we find evidence for our faith (Jn. 5:39), bases for our hope as we contemplate the faithfulness of God in fulfilling His promises (Rom. 15:4), types which foreshadow Christ and His kingdom (Heb. 8:4-5) and examples of God's dealings with man and the principles of righteousness He requires in us (Heb. 12:1-2).
"Destroy" is not used in contrast with "perpetuate" but with "fulfill." Christ did not say, "I came not to destroy, but to perpetuate." He explained, "I came not to destroy, but to fulfill." He made no promise to continue the Old Testament as a law. In fact, He did abolish the Old Testament. It is not our law.
How, then, did Christ fulfill the law and the prophets? Jesus filled up the Old Testament in His personal life by keeping it perfectly (Gal. 4:4; Matt. 3:13-15; Jn. 8:46; Heb. 4:15), thus setting an example for us (1 Pet. 2:21-22) and qualifying Himself as the sacrifice of atonement for our sins (Heb. 9:13-14; 10:1-18). The lowly Galilean made full the law by fulfilling its types (Lk. 24:44-47; Heb. 8:4-5) and completed the prophets by fulfilling their fore-tellings of the Messiah and His kingdom (Jn. 5:39; Acts 3:18-24; 13:29; 2 Pet. 1:19). He filled up the law by offering the righteousness it could not (Rom. 8:34; 10:4-10).. Jesus, in fact, fulfilled the very purpose of the law and the prophets (Gal. 3:19-25).
Since Christ has fulfilled the purpose of the Old Testament, which was "to bring us unto Christ," "we are no longer under" that law (Gal. 3:24-25). Thus, to any today who would attempt to justify themselves by any part of the law of Moses, Paul ominously warns, "Christ is become of no effect unto you …. ye are fallen from grace" (Gal. 5:4).