Frequently in his epistles, the apostle Paul goes to great lengths to describe what we call Christian liberty. In these matters God allows us freedom; he doesn't set down laws prohibiting something or commanding something. The apostle warns us against being judgmental toward our brothers, giving as an example in the Corinthian community the question about eating meat offered to idols. Paul says this has nothing to do with the kingdom of God. He says, "Those of you who have scruples about it, don't judge those who don't" and vice versa. This is a case in which we just have to respect one another.
In those admonitions, Paul uses as his basis this statement: "We are not to be judging people for whom Christ died." He reminds us that "your brother or your sister belongs to Christ. God has forgiven them. Who are you to withhold forgiveness from someone whom God has forgiven?"
Let's look at it this way. If somebody sins against me and that person repents, God forgives them. If I refuse to forgive them, can you think how ghastly that is in the sight of God? God is not obligated to forgive that person. That person has sinned against God, and God has never sinned against anybody. Here I am—a person who is a sinner refusing to forgive other sinners while God, who is sinless, is willing to forgive. Have you ever stopped to think about the arrogance that's in me when I refuse to forgive somebody that God has forgiven?
Now, how could you forgive yourself after God has forgiven you? I've had people come to me and say, "R.C., I committed such and such a sin, and I asked God to forgive me. I've gone to him ten times and asked him to forgive me, but I still don't feel forgiven. What am I going to do?" I don't have any brilliant theological answer to that. I can only tell them to ask God to forgive them one more time. When they say they've done it, I tell them this time I want them to ask God to forgive them for their arrogance. "Arrogance!?" they say. "What do you mean arrogance? I'm the most humble man in America. I've confessed this sin ten times." Doesn't God say that if you confess a sin one time, he'll forgive you? Who are you to refuse the forgiveness of God, and who are you to condemn one whom God has forgiven? That's arrogance. You may not feel arrogant, you may not mean to be arrogant, you may be rolling in humility with all of your confession. But I am telling you that if God has forgiven you, it is your duty to forgive yourself. It's not an option. You must forgive those whom God forgives, including yourself.
~ Excerpted from Now - That's a Good Question! by R.C. Sproul