What is the verdict on an unjust judge? In order to ask this, let me set a stage. This is just a scenario that will be recast in a second.

As Christians we believe that God is good. We trumpet his justice, rightness, holiness, and so on and so forth. We say that he is the true standard of what goodness and justice are. When we make judgement calls we claim to use his character as the standard of right and wrong.

And yet ... we ascribe to him something so wicked that it should make us shiver to think of it! If an earthly judge --charged by the state to uphold the laws of the state in a fair manner and himself known to be a good and upright judge-- were to knowingly acquit a guilty party we would rage against him. If a criminal proven to have committed every crime in the book from common theft to rape and murder of children, not just once but over and over and over every day of their lives, were to stand before a bench and say "your honor, guilty as charged" -- and the judge were to say "Why thank you, since you know you're guilty you are free to go and here is some money for dinner," how would we react?

Say that your child was one of those that were abused and killed by this criminal. Would you not cry out and scream about the injustice of it all and then write to the papers and get interviewed and do everything in your power to have the evil judge himself brought to justice?

Do you get the picture? We somehow inherently know that what was done was un-just. We also say that our standard of justice is God himself. And yet as Christians, instead of protesting this scenario when the scenario is cast with God as the judge, we celebrate it!

Let us recast the story.

According to our own doctrines we claim that all men are indeed guilty (Romans 3:10). We also claim to that God is a perfectly just judge. When we go on to say that he has indeed acquitted some wicked men (us) we don't even blink, as if there was no problem with this scenario. Yet according to our own inherent sense of justice, this should make him an evil judge worse than the criminals he acquits.

So here is the question: How is it that God can be truly just and yet justify wicked men?

God is in the dock. Is he defensible?
Alright, here's the non-trivial answer.

The idea is that we are all guilty.  It's pretty hard to deny this one:

Romans 3:23 (NIV)


  for all have sinned and fall short of the glory of God


Furthermore, while we are all guilty of sin, the punishment for this sin is death:

Romans 6:23a (NIV)


  For the wages of sin is death


If we go on in Romans 3, we see that the Jesus was the atonement for our sin.

Romans 3:25 (NIV)


  God presented Christ as a sacrifice of atonement, through the shedding of his blood—to be received by faith. He did this to demonstrate his righteousness, because in his forbearance he had left the sins committed beforehand unpunished


Definition of atonement


  satisfaction or reparation for a wrong or injury; amends.


So, we can see from Romans 3:25 above that Christ was the sacrifice of atonement for our sins.  

In essence, we are guilty of the sins that we commit (Romans 3:23 at top).  Because of those sins, a price has to be paid (Romans 6:23a).  Since the price had to be paid, Jesus was presented as the atonement sacrifice. (Romans 3:25).  We can receive this atonement by faith (Romans 3:25 again).

Furthermore, this debt had to be paid to show that he is just.  God is both just and righteous--being the one who deals the justice as well as the one who justifies (through the atonement for the sin).

Romans 3:26 (NIV)


  he did it to demonstrate his righteousness at the present time, so as to be just and the one who justifies those who have faith in Jesus.


Summary

God is a just God; He requires a penalty be paid for the sins we commit; and Jesus is that atonement for those sins.

Tying this in to my trivial answer, our sins create a debt that must be paid (just as our breaking the law creates a debt to society).  However, this debt has been paid already if we have faith to accept the grace given to us.