We tend to be far more ungenerous in forgiving others than God is in forgiving us. If God were to be as reluctant to forgive as we are in forgiving those who sin against us, we would be in serious trouble. As Christians we are forgiven people. We are likewise called to be forgiving people. Jesus clearly sets forth an ethic of charity in His teaching and in His behavior with those who wrong us. An unwillingness to forgive clearly has no place in the kingdom, and may in fact signal that such a one has not experienced the initial forgiveness of God in his or her life.
R.C. Sproul