Some exerpts from a Rick Warren article on forgiveness from the Spring 2006 issue of "The Worshipper" Magazine (It's not your usual "just forgive and forget" article, somewhat surprisingly):
IT ISN'T MINIMIZING THE SERIOUSNESS OF THE OFFENSE
When somebody comes and asks for your forgiveness and you say, "It's no big deal. It really didn't hurt. as if it wasn't a big deal, you don't need forgiveness, and you don't need to offer it. That actually cheapens forgiveness. Forgiveness is only for the big stuff. You don't use it for little slights that are just minor issues. If it really requires forgiveness then you should not minimize it when somebody asks you for forgiveness. [Also, they shoud not minimize it if they ask you for forgiveness.]
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IT ISN'T RESUMING A RELATIONSHIP WITHOUT CHANGE
Just saying "I'm sorry," is not enough. In fact, the Bible teaches three things are essential to resume a relationship that's been broken: repentance, restitution and rebuilding trust. You have to be genuinely repentant and truly saddened about what you did. That's not just saying, "I'm sorry." It means saying, "I was wrong. Please forgive me." ... And rebuilding trust, friends, takes a long, long time. Forgiveness is instant. When somebody hurts you, you have to forgive them immediately. But trust is something that's rebuilt over a period of time. It must be re-earned.
In our culture, most people don't get this. Whenever a political leader, a religious leader, an academic leader or anyone like this gets caught in a scandal of any kind, there will always be some people who say, "We're all imperfect. We're all human. We need to just forgive him and keep on going." Yes, you must forgive him immediately. But the Bible says trust is built on time. All leaders must have trust and credibility. It's the currency they live in. And that isn't going to happen instantly.
FORGIVENESS ISN'T FORGETTING WHAT'S HAPPENED
You've heard this phrase over and over: forgive and forget, forgive and forget. There's only one problem with it. You can't do it. It's impossible. You really can't forget a hurt that's been in your life. It's like when you go on a diet, you think about food all the time. You think about it more than when you're not on a diet. You actually focus on it. The only way you can forget something is to actually refocus on something else.
But forgetting is not what God wants you to do. There's something better than forgiving and forgetting. What's more important than forgetting is actually remembering the hurt and then seeing how God brought good out of it.
One of the greatest verses in the Bible is Romans 8:28. "And we know that all things work together for good for those who love God and who are called according to His purpose." It doesn't say that all things are good because all things are not good. Cancer is not good. Disease is not good. Death is not good. Divorce is not good. War is not good. Rape and abuse is not good. There are a lot of bad things in life that are evil. Not everything that happens in this world is God's will, but that's why we need God in our lives. ... So forgiveness isn't forgetting what happened, it's about finding what good came out of it.
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And by the way, forgiveness never eliminates the consequence of the sin. A prisoner can be repentant and be forgiven but he's still got to serve his time and pay his debt to society. There are always consequences to sin. It always hurts somebody. Forgiveness doesn't get rid of the consequences.
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You can actually pray for God to bless the person who hurt you. The Bible says, "Do good to those who hate you. Bless those who curse you. And pray for those who mistreat you." One of the ways you know you've matured, that you're a mature person, is that you can look beyond the hurt that was done to you and see their hurt and what caused them to hurt you. Hurt people, hurt people.
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Once I forgive them I can stop looking at how they hurt me and start seeing why they did it. I can actually be sympathetic and begin to pray for them, for the hurt they carry that caused them to hurt others. I relinquish my right to get even. I respond to evil with good.