What is the nature of forgiveness? If a man owes another a debt, but the man to whom it is owed says, "Forget it, I forgive your debt." does this then mean that the debt goes unpaid? No. It means that the debt is paid by the one to whom it is owed, rather than by the one who owes it or another party on behalf of the debtor. As a specific example, if I lend a man $10,000 on the agreement that they will pay it back after 3 months, only to have disaster strike and the borrower unable to repay, what happens to the debt? I can grant an extension but still require payment, I can go to court and take his possessions to pay off the debt, I can accept payment on his behalf from another, or I can "pay" it myself, meaning that I am still $10,000 poorer but he owes me nothing. This act of forgiveness is the same as payment to him.
Forgiveness is just as costly as demanding payment, only the cost is transferred from the debtor to the debt-holder.