The quintessential teaching on unforgiveness in the Bible is the parable of the unmerciful servant (Matthew 18:21–35). In this story told by Jesus, a servant's master forgives the servant's debt, a debt described as so large there would be no way to repay it. The servant, however, then seeks out a man who owes him money, a repayable amount, and pressures him to pay up. Upon hearing of the servant's actions, the master finds him and has him jailed. "So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart," Jesus concludes (Matthew 18:35). Other places in the Bible say that we will be forgiven as we forgive others (Matthew 6:14; 7:2; Luke 6:37; and others).
Unforgiveness – What does the Bible say?
However, it is important to understand that God's forgiveness as an aspect of salvation is not based on our good works. This is not karma. God's forgiveness of our sins depends entirely on Jesus' redeeming work on the cross. Because Jesus has paid our sin debt, we can receive God's forgiveness through faith. What Jesus is getting at in these teachings is that the way we treat others demonstrates our understanding of God's grace (James 2:14–26; Luke 7:47). See, Christians know that we were far from God and had no way to draw close to Him. Jesus offered Himself to take our punishment for our sins and offer us the ultimate forgiveness (Romans 5:8). Our comprehension of this great undeserved gift encourages us to offer grace and forgiveness to others. If Almighty God forgave us of a debt we could never hope to repay, how can we dare to withhold forgiveness from others? An unforgiving heart shows that we don't fully understand God's grace in our own lives.
The Bible also tells us that failing to seek peace with everyone will produce in us things we do not want. "Strive for peace with everyone, and for the holiness without which no one will see the Lord. See to it that no one fails to obtain the grace of God; that no 'root of bitterness' springs up and causes trouble, and by it many become defiled" (Hebrews 12:14–15). Unforgiveness may even give Satan an opportunity to infiltrate (2 Corinthians 2:5–11).
Even aside from these things, unforgiveness does nothing but harm our own hearts. A common saying is that refusing to forgive is like taking poison and hoping the other person will die. Unforgiveness tends to hurt the one withholding forgiveness more than the one in need of forgiveness.
This is not to say that what people do to us does not matter or that it does not hurt deeply. Forgiveness is difficult work. People really do wrong us in serious ways. But they are ultimately held accountable to God (Romans 12:19; Hebrews 10:30). Our job is to forgive them—that is, release them from the debt they owe us and lay down our right to pay back the wrong they've done to us. Of course, that does not mean that when we forgive someone for some wrong they've done that they are fully released from all consequences of their actions. They may need to make restitution, there may be civil punishment, and there may be damage done to our relationship. Forgiveness is not an automatic re-establishment of trust; we don't have to open ourselves up to repeated harm. However, forgiveness is a heart posture of grace. It is a willingness to restore what has been broken, it is a giving up of personal rights of retribution, ultimately it is a demonstration of the grace God has given us.
Unforgiveness is simply not a biblical option. Forgiving others is commanded by God and is the proper response to the forgiveness He has granted us. Ephesians 4:32 commands us, "Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you."
Why should we forgive?
How can I extend forgiveness to those who sin against me?
Is 'forgive and forget' a biblical concept?
If we sin against someone, do we need to confess to them?
Why is withholding forgiveness wrong? Since God does not forgive a person until they confess/repent, can we withhold forgiveness until a person confesses/repents?
Truth about the Christian Life