Forgiveness is the antidote to resentment, which the Big Book describes as an “infinitely grave” problem for the alcoholic (p. 66) and makes the main subject of its Step 4 inventory.
In Step 4, resentment refers primarily to holding a grudge, that is, to the kind of smoldering anger that is held over after the event that aroused the original emotion has passed. That kind of anger is always defective, for even if the initial emotion was justified, like all emotions it will always pass. Resentment is a sign that we are deliberately holding on to the anger and refusing to let it go.
As a virtue which is corrective of resentment, forgiveness is the very opposite of that. It is a disposition to give up the anger, to stop holding the perceived hurt or offense against the person and relinquish the desire to get back at her and punish her. As such, it works through the discipline of surrender. We turn the anger over. We ask God to remove it from us.
Our inventory lays the ground for forgiveness by helping us to see how deeply flawed we are and how much harm we have done. The Big Book invites us to see those we resent through the same lens, as being as flawed and indeed as sick as we are. That self-construal and that construal of others helps us to let go of the ill will which underpins resentment.
Thus, the Big Book suggests that we ask God to save us from being angry and wishing to retaliate, since we wouldn’t treat a sick person that way. It suggests that we ask God to help us treat those we resent with the same kindness, patience, tolerance, and compassion that we would treat a sick friend (p. 67)—and as no doubt we would wish others to treat us.
The implication is that we need to forgive because we too need to be forgiven. We have done as much harm to others as others have done to us. This is the angle from which the Big book introduces the notion of forgiveness. “If we are sorry for what we have done,” we are told in Step 4, “and have the honest desire to let God take us to better things, we believe we will be forgiven (p. 70).
The 12&12 picks up on this dynamic in Step 5, where we read that “This vital Step was also the means by which we began to get the feeling that we could be forgiven, no matter what we had thought or done (pp. 57-58).” We read further that “Often it was while working on this Step with our sponsors or spiritual advisers that we first felt truly able to forgive others, no matter how deeply we felt they had wronged us.” For “Our moral inventory had persuaded us that all-around forgiveness was desirable, but it was only when we resolutely tackled Step Five that we inwardly knew we’d be able to receive forgiveness and give it, too” (pp. 57-58).
In Step 5, we admit everything that is wrong with us, to ourselves, to God, and to another human being. And what happens? A big weigh falls off our shoulder. We don’t feel judged by the other person. Indeed, if the other person is in AA, he or she will actually identify with us. We don’t feel condemned by God. We do begin to get a sense that we can be forgiven. We begin to let go of the guilt we’ve been carrying all our life.
“If we ask,” the 12&12 reassures us in Step 6, “God will certainly forgive our derelictions (p. 65).” Feeling forgiven opens the way to forgiving others. This comes up in Step 8 of the 12&12, where forgiveness becomes a central virtue. Step 8 is a preliminary and preparatory Step. Its purpose is to prepare us to make amends in Step 9, where we go to the person we have harmed “in a helpful and forgiving spirit, confessing our former ill feeling and expressing our regret" (Big Book, p. 77). The 12&12 echoes this approach: “We shall want to hold ourselves to the course of admitting the things we have done, meanwhile forgiving the wrongs done to us, real or fancied" (Step 8, pp. 81-82).
Obviously, we cannot make honest and sincere amends to people we still resent. Why? Because resentment means we are still blaming others for what they did and absolving ourselves for what we did. To the extent we do that, to that extent our amends will fall short of the mark. We will be focusing on what’s wrong with them rather than on what’s wrong with us.
Furthermore, in making amends we are hoping that the person we have harmed will forgive us. We see this in the Big Book, where the story is told of one alcoholic to whom “We suggested he write his first wife admitting his faults and asking forgiveness” (p. 79).
But, the 12&12 quite logically inquires, “If we are now about to ask forgiveness for ourselves, why shouldn’t we start out by forgiving them, one and all? (Step 8, p. 78). That is of course the logic of the Lord’s Prayer, which we recite at the end of some of our meetings: “Forgives us our trespasses, just as we forgive those who trespass against us.”
The “willingness to forgive” is again highlighted in Step 10 (12&12, p. 91), while the Big Book stresses the need to ask for forgiveness in Step 11: “After making our review we ask God’s forgiveness and inquire what corrective measures should be taken" (p. 86).
If anger and resentment are a huge problem for us alcoholics, it only stands to reason that we will find forgiving a very difficult proposition. Hence the need for spiritual help. “Lord, make me a channel of thy peace,” we pray with St. Francis in Step 11, “that where there is wrong, we may bring the spirit of forgiveness,” for “It is by forgiving that we are forgiven.”
Forgiveness brings healing, to us and to those we have harmed. That’s why it’s a virtue.
"Our moral inventory had persuaded us that all-round forgiveness was desirable, but it was only when we resolutely tackled Step Five that we inwardly knew we’d be able to receive forgiveness and give it, too." – 12&12
". . . and forgive us our trespasses, as we forgive those who trespass against us . . ." – Matthew 6:12
"Real forgiveness means looking steadily at the sin, at the sin that is left over without any excuse, after all allowances have been made, and seeing it in all horror, dirt, meanness and malice, and nevertheless being reconciled to the man who has done it. That, and only that, is forgiveness; and that we can always have from God if we ask for it." – C. S. Lewis 
"Since nothing we intend is ever faultless, and nothing we attempt ever without error, and nothing we achieve without some measure of finitude and fallibility we call humanness, we are saved by forgiveness." – David Augsburger 
"Every time I try to tighten the noose of resentment around someone’s neck, I am really only choking myself. Today I will practice forgiveness instead.” – Al-Anon’s Courage to Change 
"Gratitude for being forgiven will in turn make us more forgiving and help us to let go of anger and resentment, and, as we give thanks for what has been given us so freely, we will become more generous and desire to give in equal measure." – PTP123 
