No need to follow the law at all? Then why did Jesus stated in Matthew 5:19? Was he joking?
The law is that system of legislation given by God through Moses to the nation of Israel. The entire body of the law is found in Exodus 20-31, Leviticus, and Deuteronomy, though its essence is embodied in the Ten Commandments.
The law was not given as a means of salvation (Act_13:39; Rom_3:20 a; Gal_2:16, Gal_2:21; Gal_3:11; it was designed to show people their sinfulness (Rom_3:20 b; Rom_5:20; Rom_7:7; 1Co_15:56; Gal_3:19) and then drive them to God for His gracious salvation. It was given to the nation of Israel, even though it contains moral principles which are valid for people in every age (Rom_2:14-15). God tested Israel under the law as a sample of the human race, and Israel's guilt proved the world's guilt (Rom_3:19).
The law had attached to it the penalty of death (Gal_3:10); and to break one command was to be guilty of all (Jas_2:10). Since people had broken the law, they were under the curse of death. God's righteousness and holiness demanded that the penalty be paid. It was for this reason that Jesus came into the world: to pay the penalty by His death. He died as a Substitute for guilty lawbreakers, even though He Himself was sinless. He did not wave the law aside; rather He met the full demands of the law by fulfilling its strict requirements in His life and in His death. Thus, the gospel does not overthrow the law; it upholds the law and shows how the law's demands have been fully satisfied by Christ's redemptive work.
Therefore, the person who trusts in Jesus is no longer under the law; he is under grace (Rom_6:14). He is dead to the law through the work of Christ. The penalty of the law must be paid only once; since Christ paid the penalty, the believer does not have to. It is in this sense that the law has faded away for the Christian (2Co_3:7-11). The law was a tutor until Christ came, but after salvation, this tutor is no longer needed (Gal_3:24-25).
Yet, while the Christian is not under the law, that doesn't mean he is lawless. He is bound by a stronger chain than law because he is under the law of Christ (1Co_9:21). His behavior is molded, not by fear of punishment, but by a loving desire to please his Savior. Christ has become his rule of life (Joh_13:15; Joh_15:12; Eph_5:1-2; 1Jn_2:6; 1Jn_3:16).
A common question in a discussion of the believer's relation to the law is, “Should I obey the Ten Commandments?” The answer is that certain principles contained in the law are of lasting relevance. It is always wrong to steal, to covet, or to murder. Nine of the Ten Commandments are repeated in the NT, with an important distinction—they are =not given as law (with penalty attached), but as training in righteousness for the people of God (2Ti_3:16 b). The one commandment not repeated is the Sabbath law: Christians are never taught to keep the Sabbath (i.e., the seventh day of the week, Saturday).
The ministry of the law to unsaved people has not ended: “But we know that the law is good if one uses it lawfully” (1Ti_1:8). Its lawful use is to produce the knowledge of sin and thus lead to repentance. But the law is not for those who are already saved: “The law is not made for a righteous person” (1Ti_1:9).
The righteousness demanded by the law is fulfilled in those “who do not walk according to the flesh but according to the Spirit” (Rom_8:4). In fact, the teachings of our Lord in the Sermon on the Mount set a higher standard than that set by the law. For instance, the law said, “Do not murder”; Jesus said, “Do not even hate.” So the Sermon on the Mount not only upholds the Law and the Prophets but it amplifies them and develops their deeper implications.
5:19 In returning to the Sermon, we notice that Jesus anticipated a natural tendency to relax God's commandments. Because they are of such a supernatural nature, people tend to explain them away, to rationalize their meaning. But whoever breaks one part of the law, and teaches other people to do the same, shall be called least in the kingdom of heaven. The wonder is that such people are permitted in the kingdom at all—but then, entrance into the kingdom is by faith in Christ. A person's position in the kingdom is determined by his obedience and faithfulness while on earth. The person who obeys the law of the kingdom—that person shall be called great in the kingdom of heaven.
5:20 To gain entrance into the kingdom, our righteousness must surpass the righteousness of the scribes and Pharisees (who were content with religious ceremonies which gave them an outward, ritual cleansing, but which never changed their hearts). Jesus uses hyperbole (exaggeration) to drive home the truth that external righteousness without internal reality will not gain entrance into the kingdom. The only righteousness that God will accept is the perfection that He imputes to those who accept His Son as Savior (2Co_5:21). Of course, where there is true faith in Christ, there will also be the practical righteousness that Jesus describes in the remainder of the Sermon. (Believers Bible)