It’s a simple thing to mouth the expression “forgiveness of sins” just as it is a simple thing to repeat the basic truths of Christian doctrine. Ah, yes, if all we had to do was to mouth the words! The problem is that when it comes to putting that expression into practice, we don’t know the first thing about it! You see, it is such a tremendous truth, a truth that I am to believe wholeheartedly, that all my sins are forgiven, and that by faith I am righteous before God. Oh, what a marvelously astounding righteousness this is! How totally different this is in contrast to the righteousness of this world as proclaimed by all its lawyers, intellectual giants, and philosophers! For they all reach the same conclusion, namely, that righteousness must be an inner, inherent characteristic of the human heart and soul. But this Gospel lesson teaches us that Christian righteousness is not a universal characteristic of the human heart which all share. No, Christ is teaching us that we become righteous and are freed from sins through the forgiveness of sins!
When we hear that we have been promised forgiveness of sins, we really cannot grasp that, and take this position: I have committed this and that sin; to pay for them I will do thus and so, fast “x” number of days, say “x” number of prayers, fund “x” number of poorhouses, and pay for all my sins. It’s because human nature is proud and always wants to be in control, pulling it own water bucket from the well, wants to have the honor of laying the first stone, of being Number One. That’s why this is a majestic message of divine wisdom: We must believe that our righteousness, salvation, and comfort lie outside of ourselves, namely, that we are righteous before God, acceptable to him, holy and wise, even though there is nothing within us but sin, injustice, and stupidity.
Human nature is defenseless against a bad habit; it cannot avoid an awareness of sins and yet cannot believe in pure grace and the forgiveness of sins. If you have developed this skill, of not seeing what you do see, and of not feeling what you do feel, then let me tell you something about nobler and more majestic. But I warn you, it will take you a long time to develop this artistic skill! For this business of faith in the forgiveness of sins is just as if someone were aiming a loaded gun at your face and was ready to pull the trigger, and yet you are to believe and to say, “Not to worry!”
– House Postil for Trinity 22 (Matthew 18:23-35)