There is no more important characteristic found in the human heart than forgiveness. It's importance is seen in the home, church, community and nation. Someone has said there are "three kindred spirits in the heart -- giving, thanksgiving and forgiving. Usually where one is found, all are found." A forgiving heart is an essential quality every child of God should have (Eph. 4:32).
God commands it (Mark 11:25). This should be sufficient reason for any right-thinking person to be forgiving because God's promises rest upon obedience to His word. But forgiveness on mere obedience to command usually falls short of what it should be. Anything done out of a sense of duty or necessity is usually not from the heart (cf. 2 Cor. 9:5-7). Consider the parent who makes the child say "I'm sorry" when, in reality, he is not sorry at all. He says it but only to appease his parent.
The example of Jesus (I Pet. 2:21; Phil. 2:3-5; Luke 23:34). As our example in all things, He would not require of us that which He would not do Himself. Even when His life was taken from Him, He had a forgiving attitude. It is said of Him, "He gave all, then forgave."
We have been forgiven. God, in Christ, has forgiven the sins of the Christian (Eph. 4:32). As Christ has forgiven him, he is to forgive others (Col. 3:13). One who is unwilling to forgive after he has been forgiven is viewed disdainfully by the God of heaven (Matt. 18:21-35).
In order to have future forgiveness (Matthew 6:14-15).
Forgiveness is more than just speaking the words. It must be sincere and from the heart. It must be patterned after the forgiveness God has granted to us. It must be accompanied by actions which befit true forgiveness.
Forgiveness involves a kind attitude -- abandoning all animosity and hatred. All bitterness, anger, wrath, clamor and evil speaking should be put away (Eph. 4:31). We can hold no grudges. One must deny the impulse to get even and seek to do the forgiven one good.
Forgiveness involves forgetting (Heb. 8:12), but what does it mean to forget? It is impossible for a person to completely obliterate the wrong from his mind. Rather it means to not hold the person accountable for it anymore. When forgiveness is granted that should end the matter. It should never again be dredged up or held against the one who has been forgiven.
Forgiveness should be given by the "golden rule" (Matt. 7:12). One should always be willing to forgive -- even at repeated offenses. Matthew 18:21-22 has the apostle Peter asking, "'Lord, how often shall my brother sin against me, and I forgive him? Up to seven times?' Jesus said to him, 'I do not say to you, up to seven times, but up to seventy times seven.'"