Is Substitutionary Atonement Unjust?

Christians often take substitutionary atonement for granted. However, this essential Christian doctrine can be a stumbling block for non-Christians and a point of contention for anti-theists, as substituionary atonement seems to fly in the face of personal moral responsibility, which is what we believe society to be built upon. Here are a few introductory reasons why substitionary atonement as decreed by God isn't immoral or unjust.

If God accepts Jesus' death as punishment for our sins, doesn't that make God unjust because we didn't receive the punishment we deserved and Jesus was punished undeservedly?

1. If God defines justice, what he says is just is just.

The easiest reason that substitutionary atonement is just is "because God says so". I know it sounds like a cop-out answer, but if we presume a God that is in fact God and is the ultimate judge and definer of justice, if God says something is just, it must be so. To deviate from this conclusion, you need to either claim that God knows justice but is acting unjustly and then lying about and denying His injustice (which seems incredibly petty for an all-powerful being) or you need to admit to holding a greater knowledge of justice than God himself.

2. Jesus is God, and that changes everything.

Although it may be temping to compare substitutionary atonement with paying off someone else's debt or a Tale-of-Two-Cities-esque dying in place of another, the fact that Jesus is God, holy and morally perfect, changes everything. Jesus dying for sinners is much more than Ned Stark dying for one of his bannermen (an illustration, no spoilers) and is even much more than Ned Stark dying for a Lannister. So while it certainly seems to be true that one man dying in the place of another man is unjust, we need to remember that Jesus is no ordinary man. In fact, Christianity actually affirms that one sinful man cannot provide substitutionary atonement for another sinful man, meaning that my death cannot wipe away the penalty of your sins, nor can your death mine. Jesus' deity and moral perfection make him the only worthy substitutionary atonement, the only death God will accept in the place of a sinner's.

At this point, it is still possible to make the same objection as before - how can it be just even for a morally perfect God to die for a sinner? At this point, we must admit the greatness of the mystery and the finitude of our knowledge and say "because God says so." [See point 1].

3. Yes, it certainly is injustice, in a sense.

Upon reflection, the moral perfection of Jesus, our substitutionary atonement, seems actually to make his death even more unjust, and most Christians have been deeply moved when considering the weightiness of this matter. It is true - Christ died a death he did not deserve so that those who live for him can live lives they do not deserve. It is also true - Christ was executed after a fake trial with false testimony. So in two different senses of "injustice", there certainly is "injustice" in Christ's death for us. However, in the grand legal aspect of justification, we can rest assured that God's wrath for our sins has been satisfied.

In the end, Christ's substitionary atonement, though problematic for the non-believer, causes the Christian to be immensely and humbly grateful that we have a God that loves us so. If you have friends that are struggling with this issue, I hope that God opens their eyes and you can witness their skepticism miraculously turn to gratitude.

And can it be that I should gain

an interest in the Savior's blood!

Died he for me? who caused his pain!

For me? who him to death pursued?

Amazing love! How can it be

that thou, my God, shouldst die for me?

Amazing love! How can it be

that thou, my God, shouldst die for me?