Justice is good but revenge is bad. The Old Testament law enabled justice to be done in a proportional way: a murderer would lose his own life, and the one who knocked out somebody else's tooth would lose his own. It was good for public order and kept crime to a minimum. But there was no way to modify the punishment or even forgive the offender. There was no mercy and no grace.

When Jesus announced the kingdom of heaven, He presented a very different kind of justice. The problem with the old law was not that it was too harsh, but it did not go far enough. To be truly proportional, every single sin, including wrong words and thoughts, should be punished. But the law only addressed obvious crimes which had an immediate social effect. However, to punish every sinner would have put everybody in jeopardy, because all have sinned (Romans 3:23). Jesus' kingdom was based on the fact that He would ‘become sin’ for every person (2 Corinthians 5:21) and be punished instead of them, so that all who believe in Him should not perish in judgement but have everlasting life (John 3:16).

If such grace and mercy is available from God, how should victims treat the people who hurt them? Not by taking revenge, because vengeance is only safe in God's hands! Romans 12:19-21 says, "Do not take revenge, my dear friends, but leave room for God's wrath, for it is written: 'It is mine to avenge; I will repay', says the Lord. On the contrary: 'If your enemy is hungry, feed him; if he is thirsty, give him something to drink. In doing this, you will heap burning coals on his head.' Do not be overcome by evil, but overcome evil with good." The kindness of people, who have received grace, gives room for other sinners to repent. God takes no pleasure in judgement but longs that all will come to repentance and live in His kingdom (Ezekiel 18:23).

Practically, it is a challenge. Naturally we want revenge (the old law is still in our nature), and we resist being merciful or gracious. But, with the Spirit's help we can and must be different. If God has been so patient with us, how can we be so quick to be angry with others? Jesus has given His life for sinners - should we not lay down ours for others (1 John 3:16)? No sinner deserves mercy or grace; it is given to undeserving people. That is the nature of Christ's sacrifice and the essential quality of His kingdom. Let us show that we are God's citizens: let us identify a person who has offended us, and choose to be gracious to them for Christ's sake. It is the normal way to live as a Christian.