Sooner or later, anyone reading the New Testament honestly runs into the question. Why the cross? Why does the death of Jesus sit at the dead centre of everything, sung about, painted, worn around necks? Plenty of good teachers have been killed by unjust regimes. What makes this execution the hinge of history?
The word the church uses for the answer is atonement — an old English word that means, almost literally, at-one-ment, the making of peace between estranged parties. The atonement is the answer to a question many people no longer feel the weight of: how can sinful people be brought back to a holy God? The cross is God’s answer. But to see why it took a cross, you have to start with the problem.
What sin actually costs
Modern ears hear sin as a quaint word for minor misbehaviour. The Bible treats it as something closer to treason against the source of life — a real rupture between us and God, with real consequences. Paul states the wage flatly: the wages of sin is death (Rom. 6:23). Sin is not a debt that quietly forgives itself. It is owed, and the owing is serious.
This is the backdrop against which the cross stops being arbitrary and becomes the most reasonable thing in the world. If sin were trivial, the cross would be a grotesque overreaction. It is precisely because sin is grave that the rescue is so costly.
In our place
The clearest single statement of what happened at Calvary was written seven centuries before it happened. Isaiah, describing a coming servant who suffers, says this:
Surely he took up our pain and bore our suffering… But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was on him, and by his wounds we are healed. We all, like sheep, have gone astray, each of us has turned to our own way; and the Lord has laid on him the iniquity of us all. (Isa. 53:4–6, NIV)
Read the prepositions. For our transgressions. On him. The iniquity of us all laid on him. This is substitution, and it is the beating heart of the atonement. What we had earned, he bore. The punishment that should have fallen on us fell on him instead, and the result — peace, healed — comes back to us.
Paul says the same thing in a sentence so compressed it can take your breath:
God made him who had no sin to be sin for us, so that in him we might become the righteousness of God. (2 Cor. 5:21, NIV)
An exchange takes place. He takes our sin; we receive his righteousness. He stands in our place under judgment so that we can stand in his place in favour. Nothing in our own record earns this. It is sheer gift, given at the highest possible price.
And lest anyone imagine an angry God being talked round by a kindly Son, Scripture insists the whole thing was God’s own initiative of love:
But God demonstrates his own love for us in this: While we were still sinners, Christ died for us. (Rom. 5:8, NIV)
Not after we cleaned up. While we were still sinners. The cross is not God being persuaded to love us. It is God proving he already did.
More than one angle on one cross
This taking-of-our-place is central, and the New Testament will not let us set it aside. But it is not the only thing the Bible says about the cross, and we impoverish ourselves if we stop at one camera angle. The same death that bore our punishment also reconciled us — while we were God’s enemies, we were reconciled to him through the death of his Son (Rom. 5:10). It was a victory, too: in the cross and the empty tomb that followed, Jesus broke the grip of death itself, so that death no longer has mastery over him (Rom. 6:9) — or over those who are his. The cross is one event with many facets. Hold them together and you see it whole.
A way in
If you have always found the cross either obvious or strange, try reading Isaiah 53 slowly, and then one of the Gospel accounts of the crucifixion, with this single thought held in front of you: he is there in my place. Not as a theory to assent to, but as something done for you personally.
That is finally what the atonement asks of us — not to understand a mechanism, but to receive a gift. The debt is paid. The peace is made. The only fitting response is to stop trying to earn what has already been bought for you, and to come home.