So why does it matter that your sins are almost entirely against God, regardless of what you’ve done to yourself or someone else?
There are two reasons:
1. When we sin against someone else or ourselves, we need to remember to repent to God as well. Too often, it seems we apologize to the person we wronged or, worse, “let it all blow over.” While it’s good and necessary to apologize when you’re wrong, if only 1% of your sin is against the other person, you’re missing an apology to God. It is His law that you transgressed, much more so than any infringement on someone else’s rights and you’ve harmed someone He cares about enough to die for. If you’ve sinned, go to that person, apologize, and try to make restitution, but don’t forget to ask God for forgiveness as well.
2. If God is willing to forgive everything other people have done to us and everything we have done, we have no reason to hold on to our grudges against others. There’s the parable of the unforgiving servant in Matthew 18. He owed 10,000 talents to his king (I saw online that someone calculated this to be roughly $2.25 billion, assuming an $8/hr wage), way more than any normal person could ever hope to pay off. His king forgave the debt, but then this servant grabbed his debtor by the throat and threw him in prison when the debtor couldn’t pay the 100 denarii (roughly $2,000) he owed. This unforgiving servant had just been forgiven of a debt over a million times as large, yet held this pittance against the poor debtor. When the king found out, he was furious and threw the unforgiving servant in jail until every last penny was repaid (assumedly for the rest of his life).
If sins against you are really 99% against God and He’s willing to forgive the person who wronged you, who are you to refuse to forgive the other 1%? It is God’s judgment on their sin that matters, so your refusal to forgive won’t really harm them. And it’s arrogant to put yourself above God, saying that your judgment on them is not satisfied when He claims it is.
Also, if you’ve been forgiven of such a heavy debt that there’s no way you could every pay it back, what right have you to hold the tiniest little debts that other people owe you against them? There can never be anything done to you that’s worse than what you do to God every time you sin, so there’s never any reason to withhold forgiveness.
Both of these are reasons we should forgive, but there’s a reason we must forgive that goes beyond even these…