How is it just for God to put someone’s sins on Jesus, making them sinless? I have heard the analogy of a judge fining someone, and then paying the fine on their behalf; but sin is surely really, really bad, and no court would allow a judge to die instead of a criminal who had been given the death sentence.
After talking through the gospel with friends, this seems to be a big sticking point. How can a murderer seemingly get away with what he’s done and go to heaven, while Johnny Average gets punished–solely on the basis of whether he accepts Jesus? It is loving on God’s part to give everyone the chance of salvation, and it is just for him to punish unrepentant sinners, but how is it just for God to forgive a repentant sinner, who though repentant still sins?
I think you might be confusing “just” with “fair.”
Justice is about making sure that someone pays the penalty for a wrongdoing. Fairness is about treating people appropriately and right.
It is just for God to insist that someone pay the penalty for sin. It wasn’t fair for Jesus to pay that penalty Himself, because that’s about grace, not justice. Someone has said that justice is getting what we deserve, mercy is not getting what we deserve, and grace is getting what we don’t deserve. I find those distinctions very helpful.
It is just for God to forgive a repentant sinner who continues to sin (that would be all of us!) because all of our sins, those committed before salvation and all those committed after salvation, were all paid for at the cross. Maybe I can help with the “sticking point” with a very simple word picture: we are all standing at the bottom of the waterfall of God’s love and grace. Those who refuse to turn to God in trustful dependence, receiving His forgiveness and salvation, have their cups upside down and therefore can’t receive what God is pouring out on them. Those who have trusted Christ have turned their cups right side up, and can receive what God is offering.
One of the most amazing truths about the gospel is that our sins are transferred to Jesus, who paid for them at the cross, and His righteousness is transferred to us. It is the most absurdly unfair transaction in the history of all creation, but it’s true. Love does things like that.
Hope this helps.