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?