Our Scripture reading last Sunday included the Parable of the Unjust Steward (Luke 16:1-15), which is probably one of the toughest parables to make sense of. A household manager gets sacked because of his corruption, so before he cleans out his desk he discounts the debts of everyone in debt to his master as a way to get in good with them for when he’s out of a job. And even though the Unjust Steward is cheating him out of what is his due (telling people who owe 100 measures of oil they only need to pay 50), the Master commends him.
Though my take on it is not exactly how our Pastor Douthwaite took it (for that, see St. Athanasius Lutheran Church: Pentecost 18 Sermon), something he said made the parable click for me. When someone sins, the primary person being sinned against is God. So when we forgive someone for sinning against us, we are setting aside what is owed to God. And God wants us to do that!