Zeal For Truth

You have probably heard a common Christian argument that goes something like this:

God is completely holy and cannot abide the presence of sin. Since God is also completely just, He cannot allow sin to go unpunished. He cannot simply forgive sin without there being some sort of satisfaction for sin (this argument typically focuses on personal sins, and not original sin).

We of course, can do nothing ourselves to either earn forgiveness by works or by punishment we suffer. God then sent Jesus, who suffered the penalty for our sins, and therefore we can have forgiveness through faith in Jesus. God is still holy and just because Jesus’ death takes away our sin and sin is punished.

An example of this is a well-known email that has made its rounds around the world. It depicts God as a judge who finds the defendant guilty. He then takes the penalty on himself, and is then able to pardon the defendant since the offense had been paid for. The idea is that if God had simply pardoned the defendant without there being a penalty paid, then God would be unjust judge that allowed sin to exist without punishment (implicitly endorsing it).

My question is: how exactly is it just that the innocent is punished for the guilty? Furthermore, with the whole Trinity concept, Jesus is God. So, not only is an innocent party punished, it’s actually the party the was wronged that is punished (defining sin as an offense against God). But somehow, this innocent and wronged party (the Trinity) couldn’t, or perhaps wouldn’t, forgive us until He had been had taken the penalty Himself.

I understand from the perspective of grace, but how can it be termed just?