Jesus did not bring a new law when He appeared in the flesh. His purpose was not to abolish the Law of Moses, but to fulfill it (Matt. 5:17). He did this first of all by keeping the real moral demands of the Law. (Morality refers to relationships, whether it be with God or with one another.) Secondly, He made the ceremonial ordinances become real in Him. He became, for example, the ultimate sacrifice to which all the animal sacrifices had pointed. We must not look for a new law in the New Testament scriptures, but rather listen to what Jesus has to say about the old: "This is my Son, whom I love. Listen to Him!" (Mark 9:7).
Why would God have given Israel such a detailed law, only to have Jesus rebuke the people for following it? Our Lord rebuked those who did not keep the Law: "But you have neglected the more important matters of the law--justice, mercy, and faithfulness" (Matt. 23:23). His purpose was to show how very little the people really understood about the moral demands of the Old Testament. We know that Jesus kept the Law of Moses perfectly and so became an acceptable atoning sacrifice for all the sins of the world. This should tell us something about the all encompassing nature of the Law. If the Law had not taught all of our duties both towards God and one another, then Jesus' obedience to the Law would have been meaningless.
In the Sermon on the Mount, Jesus was not adding to the requirements of the Law. He was confronting the narrow oral interpretation that had grown up around the Law. Even a casual reading of the gospels with an annotated Bible will demonstrate the high regard Jesus had for the written word of the Old Testament. He resisted the temptation of Satan, saying It is written .... In contrast, he belittles the oral teachings with their legalistic interpretations of the Law: "You have heard...".
Let us take for example, Jesus' teaching on adultery.
"You have heard that it was said, 'You shall not commit adultery'; but I say to you that every one who looks on a woman to lust for her has committed adultery with her already in his heart" (Matthew 5:27-28).
It is true that the Law did not impose a penalty for lust until it had led to an actual sexual encounter. This makes sense, because only God can see into a person's heart, and civil penalties were imposed by the civil magistrates. Of course, God could have simply zapped those with lust in their hearts, but it has never been God's desire to destroy the hardhearted, but rather to give them a new heart of flesh.
Nevertheless, there are passages in the Old Testament that indicate an individual is held accountable by God for the intentions of his heart. For example in Gen. 6:5 as God prepares to destroy the world by flood:
"The Lord saw how great man's wickedness on the earth had become, and that every inclination of the thoughts of his heart was only evil all the time."
In I Kings 8:18, we see that the Lord approved David simply "Because it was in your heart to build a temple for my Name, you did well to have this in your heart." (David was not allowed to build the temple, but his son was granted the privilege.)
The tenth commandment of the covenant made at Mt. Sinai addresses the deepest intentions of the heart:
"You shall not covet your neighbor's house. You shall not covet your neighbor's wife, or his manservant, or maidservant, his ox or donkey, or anything that belongs to your neighbor" (Ex. 20:17).
Adultery (Ex. 20:14) and stealing (Ex. 20:15) had already been forbidden in previous commandments. So this commandment must refer to something other than the actual taking of one's neighbor's ox, for example. This commandment addressed the innermost desires of the heart, and pointed to the internal nature of all of God's law. We are not to begrudge our neighbor any of God's blessings, whether it be the quality of his life ("do not murder"), the happiness of his marriage and his family life ("do not commit adultery"), his possessions ("do not steal"), and so on.
Jesus was not changing God's law. It was never okay with God that Israel lust or covet in their hearts. Job, with deep moral insight, said:
"I have made a covenant with my eyes not to look at a girl...If my heart has been enticed by a woman, or if I have lurked at my neighbor's door, then may my wife grind another man's grain, and may other men sleep with her" (Job 31:1, 9-10).
Let us look at another Old Testament law that gives people problems. This is what Jesus has to say about the oral interpretation of the so-called law of retaliation:
"You have heard that it was said, 'Eye for eye' and 'tooth for tooth.' But I tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also. And if someone wants to sue you and take your tunic, let him have your cloak as well..." (Matt. 5:38-40).
Some people have concluded from this passage that the Law of Moses demanded full retribution against offenders, while Jesus demands the opposite: "Do not resist an evil person." Carried to its logical extreme this non-resistence would mean not only pacifism in war, but allowing burglars to enter our home unchecked, rapist and murders to have their way with our children, and the disbandment of our army, navy, airforce, and even our local police force. We are surely misunderstanding Jesus if we believe he is advocating total non-resistance to evil. Paul himself warns that governing authorities are "a minister of God, an avenger who brings wrath upon the one who practices evil" (Rom. 13:4).
Jesus is not changing the Law, but rebuking the misuse of it. This law of "tooth for tooth" or "life for life" never allowed for personal vendetta or vengeance. Rather, it was given in the context of the covenant code (Ex. 21-23) which was addressed to the "judges" (Ex. 21:22) who were to give "judgments" (Ex. 21:1) in cases of civil dispute. The Jews were using this law to justify their own personal hatred and desire for revenge.
This principle of "life for life" had been given as a general guideline to the magistrates to make sure that the restitution matched the loss. Not more, and not less than the loss was to be required of the wrongdoer. Even so, this "life for life" or "tooth for tooth" was not meant to be taken literally, nor did it permit personal retaliation. The wrongdoer was guilty before God and had to make restitution to God (Num. 5:6-8), as well as make direct restitution to his victim or the victim's family. Yet, even in those cases where the victim had lost his life, Numbers 35:31 indicates that a substitution was allowed for the offender's life in every case but premeditated murder.
Jesus insists that the Law never allowed for personal hatred or vengeance: "If someone slaps you on your right cheek, turn to him the other also." Jesus is telling us to go to the other extreme, rather than to harbor vengeful thoughts in our hearts: "If someone wants to sue you and take your tunic (having won the civil case), let him have your cloak also." "If someone forces you to go one mile (Roman law required the Jews to carry burdens for the Romans a distance of one mile), go with him two miles."
Concerning a related topic, Jesus said, "You have heard that it was said, "Love your neighbor, and hate your enemy. But I tell you: Love your enemies and pray for those who persecute you... Be perfect, as your heavenly Father is perfect." The Jews may have heard it was okay to hate their enemies, but no such statement was ever made in the written word of the Law. Again Jesus is rebuking the narrow oral interpretation that had grown up around the Law. God never allowed the hatred of one's enemies. All of man's duties both toward God and his neighbor had been taught in the Old Testament. Rom. 12:17-21, for example, simply repeats the moral exhortations found in the Old Testament writings. "Do not repay anyone evil for evil" (Prov. 20:22; 24:29) for "It m mine to avenge, I will repay" says the Lord (Deut. 32:35). Instead, ".if your enemy is hungry give him food to eat; if he is thirsty, give him water to drink. In doing this you will heap burning coals on his head, and the Lord will reward you" (Prov. 25:21-22). Even an enemy's ox or donkey were to be treated with kindness (Deut. 22:1-4). The greatest passage on loving all of mankind is found in Leviticus 19:17-18:
"Do not hate your brother in your heart. Rebuke your neighbor frankly so you will not share in his guilt. Do not seek revenge or bear a grudge against one of your people, but love your neighbor as yourself."
Jesus did not have a problem with the Law, anymore than Paul did. Paul called the Law "holy," "just," "good" and "spiritual" (Rom. 7:12-14). The Law itself so perfectly taught God's complete will for us that "if a law had been given that could impart life, then righteousness would certainly have come by the law" (Gal. 3:21). We must not look for a new law whereby we may be justified before God. The problem was with Israel's heart, and with our hearts. The Law was given to bring us to Christ (Gal. 3:21) and was never intended as a possible way to earn eternal life. What the Law lacks is an inner motivation. It could teach us how to perfectly love God and one another, but it could not compel us to do so. Jesus accomplishes in His disciples what the Law could not. Because God no longer holds us accountable for breaking His law, our heart's desire is to love Him and one another. We grow in love day by day, trusting always in His forgiveness.