Let us start with a different question to better frame the one above. Why be just or fair? At the very least, we obey laws so we are not punished. At higher levels, we strive for fairness because we have come to be fair people and to deny justice is to deny whom we are as persons.
When it comes to forgiveness, we cannot fall back on laws and punishments because no society ever has had a law requiring forgiveness because it is centered in mercy, not on a quest for fairness.
I would like to suggest that there are at least four good reasons to forgive:
1) As we forgive, we begin to feel better emotionally. Forgiveness is not centered in the self, but instead on goodness toward those who have injured us. A *consequence* of forgiving is emotional release from resentment. This by no means implies that a person is necessarily selfish if he or she forgives for this reason. Grasping a life preserver in a stormy sea is a wise move.
2) As in our justice example above, as we practice forgiveness over and over, we actually become forgiving persons. To forgive becomes a part of who we are as persons and to not forgive is to deny our very personhood.
3) When we practice forgiveness long enough, we begin to see that we have a choice in life regarding the legacy we will leave in this world. We can leave a legacy of woundedness and anger or a legacy of love. Forgiveness helps us to leave a legacy of love as we honor each person as having inherent worth, even those who have hurt us. We do not honor the unjust for what they have done, but in spite of that.
4) Finally, as we forgive, we are showing others how to live a life of moral goodness in the face of unjust treatment. When we forgive, we are helping to create a community of forgiveness for others, in the home, school, place of employment, place of worship, and wherever people come together for mutual support and growth.