WHY?
But why doesn't God just forgive us? Why does anyone have to suffer at all?
The first thing to say is that forgiveness of any serious transgression means someone has to suffer. If you have forgiven a painful injury, you know how much it hurts to refuse to get even, let alone seek vengeance, and instead to forgive.
The second thing to say, however, is that the Cross is more than just an elaborate, and shocking, symbol of God's self-sacrificial forgiveness. The Cross takes care of something; it accomplishes something.Many of the world's religions speak of wrong actions as affecting the order of things, not just making the gods or other people or oneself unhappy. In India, when one fails to do what one should, one's negative actions create negative karma. In tribal societies around the world, breaking tabus, whether one meant to do so or not, creates a bad situation that requires corrective action. And in ancient Israel, failing to follow God's law, even in unintentional transgression, was called sin, and required an appropriate sacrifice.Christianity shares this sense that sin is not only a rupture in our relationship with God and others. Such a rupture could be met indeed with forgiveness.
Sin also somehow makes a mess, incurs a debt, infects a soul, and so on in a range of metaphors that all point to a problem in the nature of things that needs solving.
Five-year-old Billy uses his crayons to decorate Mom's heirloom Irish linen tablecloth. He has been told not to do so, and he does it anyway. When Mom calls him to account, Billy sees how sad she is and repents. Mom forgives him. All is well, except that the tablecloth still needs washing. The relationship of Mom and Billy is restored by forgiveness, but someone still needs to take care of the objective state of affairs caused by Billy's sin.
I owe you a thousand dollars. It's time to pay up, and I tell you that I need the money for something else. You compassionately see my side of things, and you decide to forgive the loan, and forgive me. We thus remain friends. But the fact remains that you are out a thousand dollars. Either I pay it, or you do, no matter how we feel about each other.
In the Cross of Christ there is a disorder that is rectified, a stain that is removed, a disease that is cured, a penalty that is paid, a something wrong that is made right by Jesus' sacrifice of himself. Jesus anticipates that horrible reality in the Garden of Gethsemane and acknowledges that the cup of suffering must be drained by someone, either us or him. However we feel about him and however he feels about us, the cup is still there. And he chooses to drink it on our behalf.