Your analogy is off. It's more like the judge forgives the debt and then pays it himself, not having your brother pay it.
The debt is owed God so why would God have to pay himself and why did God come up with this cruel bloody rule that an innocent person will be murdered to pay the debt off? Is God to weak or powerless to just forgive sin and not have to go through this unrelated torture of a sinless person?
Would God take pleasure in torturing, humiliating and murdering Himself?
Think about this: Sinning against God is unbelievably huge, so would a totally unpayable debt be greater than a debt that could be paid?
How is it forgiven *and* paid for?
Suppose a friend comes over to your house and breaks your lamp. You tell your friend that you forgive him and he doesn't owe you anything. You still need to replace the lamp, and since you've forgiven your friend, YOU are the one who pays for the lamp. So the breaking of the lamp is both forgiven and paid for.
Our sin is breaking the lamp. God forgives us, we don't pay for our sin. God then paid for the sin Himself (through Jesus).
We are not talking about anything that can be “replaced” since there is no way to “replace” rebellious disobedience directly against God with anything. Would you have me believe God torturing, humiliating and murdering Christ would “replace”/satisfy what I did?
One may argue that is more "loving", but "love" is not the sole quality of God. God has another quality - He is just. There must be justice. Sin just being ignored and swept under the rug would not be justice.
Think about this:
There is a, one of a kind, Tiffany vase on your parent’s mantel that has been handed down by your great grandmother. You, as a young person, get angry with your parents and smash the vase. You are later sorry about it and repent and your loving parent can easily forgive you. Since this was not your first rebellious action your father, in an act of Love, collects every little piece of the vase and you willingly work together with your father hours each night for a month painstakingly gluing the vase back together. The vase is returned to the mantel to be kept as a show piece, but according to Antique Road Show, it is worthless. Working with your father helped you develop a much stronger relationship, comfort in being around him and appreciation for his Love.
Was your father fair/just and would others see this as being fair treatment? Did this “punishment” help resolve the issue?
Was restitution made or was reconciliation made and would you feel comfortable/ justified standing by your father in the future?
Suppose after smashing the vase, repenting and forgiveness, your older brother says he will work with your father putting the vase together, so you can keep up with your social life. Would this scenario allow you to stand comfortable and justified by your father?
Suppose Jesus the magician waved his hands over the smashed vase and restored it perfectly to the previous condition, so there is really very little for you to be forgiven of or for you to do. Would this scenario allow you to stand comfortable and justified by your father?
What are the benefits of being lovingly disciplined?
Suppose it is not you that breaks the vase but your neighbor breaks into your house because he does not like your family being so nice and smashes the Tiffany vase, but he is caught on a security camera. Your father goes to your neighbor with the box of pieces and offers to do the same thing with him as he offered to do with you, but the neighbor refuses. Your father explains: everything is caught on camera and he will be fined and go to jail, but the neighbor, although sorry about being caught, still refuses. The neighbor loses all he has and spends 10 years in jail. So was the neighbor fairly disciplined or fairly punished?
How does the neighbor’s punishment equal your discipline and how is it not equal?
Was the neighbor forgiven and if not why not?
Justice is not served by having just “someone” pay for rebellious disobedience, since justice requires the offender to be disciplined and not some willing innocent individual?
When there is a monetary debt, courts allow substitutionary payments all the time. They don't care who pays, just as long as it is paid. We don't typically allow substitutionary payments for jail time, because that is something you can pay. If you have no money, it doesn't matter, you don't need money to spend time in jail. God allows substitutionary payment for sin because the price is one that you simply can't pay. There's no other way to pay the debt to God than to have someone else other than us pay it.
We are talking about rebellious disobedience and not some monetary debt. Having God punish a willing Christ by torturing, humiliating and murdering him is not just, fair, or Loving for the guilty party (us). We need Loving personal disciplining by our Father.
If the innocent *volunteers* to pay it because you can not, I don't see the injustice. And don't forget the Judge who imposed the sentence is the innocent One volunteering to pay it.
In any court the judge would be unfair/unjust to torture and murder an innocent person (even a willing volunteer) to allow the guilty to go free.