For the rest of the chapter Jesus corrects his listeners understanding of the law. He’s going to speak on anger, lust, divorce, oaths, retaliation, and love. Each section he begins by stating some form of the phrase: ”you have heard that it was said; … but I say to you.” Again, Jesus is not giving another law as if the Old Testament laws were incorrect or incomplete. Rather he is correcting his listeners understanding of those very same laws.
“You have heard that it was said to those of old, ‘You shall not murder; and whoever murders will be liable to judgment. ’ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ‘You fool! ’ will be liable to the hell of fire. So if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there before the altar and go. First be reconciled to your brother, and then come and offer your gift. Come to terms quickly with your accuser while you are going with him to court, lest your accuser hand you over to the judge, and the judge to the guard, and you be put in prison. Truly, I say to you, you will never get out until you have paid the last penny. -Matthew 5:21–26 ESV
Jesus is teaching the heart of murder is anger; or anger is principally murderous. The hearers of the day knew they would be liable to judgment if they lifted their hand and killed another person. They did not however understand that they would be equally liable to judgement if they merely lifted their heart in anger toward another. This is the principle behind the command in Exodus 20 to not murder. Jesus wants us to know it is not enough to merely conform outwardly to an external law. To be right with God, one must love his neighbor inwardly, and therefore not be subject to the guilt of judgement.
Jesus also wants us to know that fulfilling the law of love is not only concerned about our own heart, but the heart of our neighbor. The two illustrations in our section of Scripture are concerned about the possibility of another person being angry with us.
The first has to do with bringing an offering to God. Jesus tells us that if we remember another person has anger in his heart towards us, we are to first go and be reconciled with that person before we bring the Lord our offering. God is concerned equally with your brother’s anger as well as your own. If you are the cause of someone else’s anger, your duty of love is to become the remedy and solution to their anger. Our redeeming Lord renews the sinner’s memory. If he brings to your memory an offense you may have caused another person, you are to make it your high priority to make things right.
The second illustration has to do with a person making an accusation against you. This person desires to bring you to court because he is angry with you for some reason. Paul wrote a half chapter in 1 Corinthians 6 dealing with this same issue. He tells us it is a shameful thing for a believer to head off to an earthly courtroom. He exhorts us in verse 7–8:
Why not rather suffer wrong? Why not rather be defrauded? But you yourselves wrong and defraud—even your own brothers!
There is no earthly courtroom that can judge and sentence a person for the crime of anger. But Jesus teaches us that every murder that happens here on earth was born first from a heart of anger. Anger is principally murderous.