Now, it seems to me that we often make a mistake both about God’s forgiveness of our sins and about the forgiveness we are told to offer to other people’s sins. Take it first about God’s forgiveness. I find that, when I think I am asking God to forgive me, I am, in reality (unless I watch myself very carefully), asking Him to do something quite different. I am asking Him not to forgive me but to excuse me. But there is all the difference in the world between forgiving and excusing. Forgiveness says, “Yes, you have done this thing, but I accept your apology, I will never hold it against you, and everything between us two will be exactly as it was before.” But excusing says, “I see that you couldn’t help it or didn’t mean it; you weren’t really to blame.” If one was not really to blame, then there is nothing to forgive. In that sense, forgiving and excusing are almost opposites. Of course, in dozens of cases, either between God and man or between one man and another, there may be a mixture of the two. Part of what seemed, at first, to be the sins turns out to be really nobody’s fault and is excused; the bit that is left over is forgiven. If you had a perfect excuse, you would not need forgiveness. If the whole of your action needs forgiveness, then there was no excuse for it.
But the trouble is that what we call “asking God’s forgiveness” very often really consists in asking God to accept our excuses. What leads us into this mistake is the fact that there usually is some amount of excuse, some extenuating circumstances. We are so very anxious to point these out to God (and to ourselves) that we are apt to forget the really important thing, that is, the bit left over, the bit which the excuses don’t cover, the bit which is inexcusable but not, thank God, unforgivable. And, if we forget this, we shall go away imagining that we have repented and been forgiven when all that has really happened is that we have satisfied ourselves with our own excuses. – C. S. Lewis (1898-1963)
From: “On Forgiveness” in The Weight of Glory and Other Addresses by C. S. Lewis; 2nd edition edited by Walter Hooper (New York: Macmillan, 1980). First edition published in 1949.