For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins. (Matthew 6:14)
Sometimes it's so difficult to forgive; especially when the wound is deep in the spirit. The physical pain or the mental agony or both endured can bring bitterness, rage and an attitude of vengence and this can last for years. There are many who justify the keeping of such feelings but the Bible advocates forgiveness.
The extent to which a person can forgive the offender varies and in the case of believer's it depends on spiritual maturity.
Bitterness, rage and a vengeful attitude caused by an unforgiving attitude can often bring about bodily sickness to the one having it.
The Biblical viewpoint regarding forgiveness is clear. For God to forgive our sins, we must forgive the sins that others commit against us.
Once Peter came to Jesus and asked, "Lord, how many times shall I forgive my brother when he sins against me? Up to seven times?" Jesus answered, "I tell you, not seven times, but seventy-seven times. (Matthew 18:21, 22)
Jesus also said, "And when you stand praying, if you hold anything against anyone, forgive him, so that your Father in heaven may forgive you your sins." (Mark 11:25)
And how must the forgiveness be? Often we may forgive others with our words, yet we may hold a grudge against them.
Jesus warned his disciples regarding such an attitude saying,
"This is how my heavenly Father will treat each of you unless you forgive your brother from your heart." (Matthew 18:35)
So forgiveness that God expects is that which comes from the heart. Difficult yet possible because God has given the Holy Spirit to those who believe in Jesus.
And may God give us the spiritual strength needed to have a forgiving attitude at all times.