The story is preached from the street corner to pulpits around the world: Humans are sinners all sin demands repayment (justice), but the "good news" is Jesus paid the debt. It is a fine story. But it is not Gospel.
When framed this way, Christ does not forgive the debt of sin but only pays it off. Meaning that God is still a God who demands a tit-for-tat. Every sin requires a payment. Every debt is due. At the end of time, all accounts will balance. This sense of balance is often described as justice, which makes us feel good, but it is not Gospel.
Rather than paying the debt, Jesus forgives the debt. To forgive a debt means that the debt that was owed is erased. To pay the debt means the debt is still there but now it is balanced. God who demands the debt to be paid is not the God of the radical grace and love that Jesus points us to. This pay-the-debt god is a false idol that we place our trust in because it "makes sense" that every debt is to be paid.
The Gospel of Jesus Christ is one that does not "make sense" in so many ways. The Gospel is one that proclaims that there is no debt to pay off. It is, and you are, forgiven. If you have to have a ledger page to show it, the debt line has been erased - as though it was never owed to begin with.
It is a nice story, Jesus pays our debt, but this story maintains a social order built upon score keeping, grudge holding, and gracelessness. It is not Good News.