Interestingly, in the model prayer (Matthew 6:12), sin is expressed as debt. It is a true metaphor because duty neglected in relation to God is a debt owed to Him, one that must be discharged by paying a penalty. All have sinned (Romans 3:23), and the wages of sin is death (Romans 6:23). We are all under a peculiar form of indebtedness that we cannot pay and still have hope!
Simon and the woman each portray a class of sinners. Though all are sinners, some have incurred more debt through the way of life each has lived. Some are outwardly respectable, decent, and clean living, while others have fallen into gross, sensual, and open transgression. In this regard, Simon was a great deal "better" than the woman, who was coarse and unclean. She had been wallowing in filth while he attained civic respectability through rigid morality and punctilious observance of civility. He had far less to answer for than she, but he had also received a great deal more from his morality and righteousness than she had. God is not so unfair as to withhold blessings from people for the right they have done. Yet, regardless of the relative size of each one's debt, neither was able to pay it!
We all are sinful and stand in the same relation to God as these two debtors. One's sins may be blacker and more numerous than another's, but upon considering degrees of guilt and the complex motivations behind each one's sins, we may not be so quick to judge the woman's sins worse than Simon's. From this perspective, they were equal. His sins were clothed with respectability, but he still could not meet his debt. Jesus says, "They had nothing to pay." That also precisely describes our position in relation to each other.
What does this mean practically in regard to Jesus Christ and our sins? No depth of guilt, no amount of tears, self-flagellation, or discipline, no amount of repentance can work this into a payable debt. Some of these are certainly required of God and are good to do, but forgiveness, the payment of our debt incurred through our personal sins, is by grace through faith (Ephesians 2:8). It comes by God's mercy through the blood of Jesus Christ (I John 1:7). We absolutely cannot pay it ourselves and still have hope of eternal life. If it could, God would owe us something—He would be indebted to us! That will never, never be.
John W. Ritenbaugh
An Unpayable Debt and Obligation