mmyke..

The idea behind 'God does not forgive monetary debts' is that this is other ppl's right. Allah forgives what's between Him and His creation, but when it comes to other ppl's rights we have to clear ourselves before we die, otherwise we'll have to pay back on the day of judgment, in which case we'll have to compensate them in 'heavenly credit' not in cash.

This is of course meant to encourage ppl to be honest and responsible to each other.