Mercy vs. Justice and the Barbarity of Human Sacrifice

Intriguing clarification arrived in the ongoing exchange:

One of Rob's premises is that God rewards or punishes based on belief. That is a true premise, but he concludes from that premise that God is unjust. I conclude from that premise that God is merciful, since my belief in Christ's sacrifice allows me to escape that which should be rendered due to me. ...God's justice has not been ignored, but still satisfied. If a judge concluded a criminal could go free we would say that is unjust, but someone else said "I'll do the time so justice is fulfilled" then we are receiving mercy and it is because someone else is taking for us what should be rendered due for the crime. ...I conclude God to be merciful and not unjust

The conclusion is that He's merciful and not unjust? But mercy conflicts with justice: justice means getting what you deserve, while mercy means getting what you don't deserve.

Suppose Bugsy murders someone. Justice doesn't involve just any fellow being executed as some sort of generic payment to the Cosmos, nor even someone who volunteers to take one for the team -- it is Bugsy being executed that brings him his due. Justice here doesn't call for just any payment to be made, it calls for a payment by the offender. This example involving a judge isn't allowed in our courts precisely because it is unjust for the bad guy not to do his time, whether or not someone else wants to take his place. Pinch hitting may work for baseball, but not for prison time.

But there's something a lot more disturbing going by here...

Mercy is the injustice of giving the unearned; taking the unearned is theft or parasitism. Injustice, theft, and parasitism. Who wants to enable and encourage those in themselves and others? Not me, they are all bad. The practice of human sacrifice is barbaric and evil precisely because it combines them on a grand scale, at the level of entire lives. Appeasing volcanoes with barbecued virgins, helping the sun rise with fresh Aztecan hearts, sacrificing an innocent to benefit the wicked -- these are all monstrously bad in practice and moral policy.

I recoil when I find people embracing human sacrifice and making it central to their most cherished institutions.