The whole concept of debt...

In the Bible, as in Mesopotamia, “freedom,” came to refer above all to release from the effects of debt. Over time, the history of the Jewish people itself came to be interpreted in this light: the liberation from bondage in Egypt was God’s first, paradigmatic act of redemption; the historical tribulations of the Jews (defeat, conquest, exile) were seen as misfortunes that would eventually lead to a final redemption with the coming of the Messiah...
   In this light, the adoption of the term by Christians is hardly surprising. Redemption was a release from one’s burden of sin and guilt, and the end of history would be that moment when all slates are wiped clean and all debts finally lifted, when a great blast from angelic trumpets will announce the final Jubilee.
  If so, “redemption” is no longer about buying something back.   It's really more a matter of destroying the entire system of accounting. In many Middle Eastern cities, this was literally true: one of the common acts during debt cancellation was the ceremonial destruction of the tablets on which financial records had been kept, an act to be repeated, much less officially, in just about every major peasant revolt in history.
This leads to another problem: What is possible in the meantime, before that final redemption comes? In one of his more disturbing parables, the Parable of the Unforgiving Servant, Jesus seemed to be explicitly playing with the problem:

Therefore, the kingdom of heaven is like a king who wanted to
settle accounts with his servants. As he began the settlement, a
man who owed him ten thousand talents was brought to him.
Since he was not able to pay, the master ordered that he and
his wife and his children and all that he had be sold to repay
the debt.
The servant fell on his knees before him. “Be patient with
me,” he begged, “and I will pay back everything.” The servant’s
master took pity on him, canceled the debt, and let him go.
But when that servant went out, he found one of his fellow
servants who owed him a hundred denarii. He grabbed him
and began to choke him. “Pay back what you owe me!” he
demanded.
His fellow servant fell to his knees and begged him, “Be
patient with me, and I will pay you back.”
But he refused. Instead, he went off and had the man thrown
into prison until he could pay the debt. When the other ser-
vants saw what had happened, they were greatly distressed and
went and told their master everything that had happened.
Then the master called the servant in. “You wicked servant,” 
he said, “I canceled all that debt of yours because you
begged me to. Shouldn’t you have had mercy on your fellow
servant just as I had on you?” In anger his master turned him
over to the jailers to be tortured, until he should pay back all
he owed.”

   This is quite an extraordinary text. On one level it’s a joke; in others, it could hardly be more serious. We begin with the king wishing to “settle accounts” with his servants. The premise is absurd. Kings, like gods, can't really enter into relations of exchange with their subjects, since no parity is possible.  And this is a king who clearly is God. Certainly there can be no final settling of accounts.  So at best we are dealing with an act of whimsy on the king’s part.  The absurdity of the premise is hammered home by the sum the first man brought before him is said to owe. In ancient Judaea, to say someone owes a creditor “ten thousand talents” would be like now saying someone owes “a hundred. billion dollars.” The number is a joke, too; it simply stands in for “a sum no human being could ever conceivably repay.”"
Faced with infinite, existential debt, the servant can only tell obvious lies: “A hundred billion? Sure, I'm good for it! Just give me a little more time.” Then, suddenly, apparently just as arbitrarily, the Lord forgives him.
Yet, it turns out, the amnesty has a condition he is not aware of. It is incumbent on his being willing to act in an analogous way to other humans-in this particular case, another servant who owes him (to translate again into contemporary terms), maybe a thousand bucks.  Failing the test, the human is cast into hell for all eternity, or "until he should pay back all he owed," which in this case comes down to the same thing.  

   ...what is... striking to me is the tacit suggestion that forgiveness, in this world, is ultimately impossible.  (Debt: The First 5,000 Years by David Graeber: 82-84)