So, in your mind, it's just if I take the place of my sociophatic friend - if I serve his prison sentence for murdering, I don't know, a family of five? This would be "godlike" justice, would it? This would pardon my friend and justice would be served? For whom would justice be served? This might be the most immoral idea I've heard.
God invents "sin", he invents a punishement for sin, death, and he then pardons the sinners and pays their penalty? Please, this is supposed to be justice? It's a twisted game is what it is. Thank god there's no good reason to believe any of it is true.
You seem to think there's some "justice" that is independent of other people. You say "God knew the penalty must be paid or justice is not served." Justice to whom? Can't be god if he's paying for it - that would be absurd. Can't be other people, we deal with injustices within society on our own and most of us find "the death penalty" immoral and inexcusable. So who or what exactly needs to be paid here? To whom is this justice? You've made so many self-contradictory turns to reconcile the blatant flaws and contradictions in this ideology, you've actually found yourself deep enough that you can no longer see the forest for the trees.
Believe in god if you think there is good reason to, but please, don't pretend as if this makes sense.