When Jesus was hanging on the cross, the chief priests, scribes, and elders mocked Jesus, saying, “He saved others; he cannot save himself. He is the King of Israel; let him come down now from the cross, and we will believe in him.
Here’s an excerpt from the book, where Carson explores what would have happened if Jesus had taken them up on the challenge and came down from the cross.
This would be a pretty remarkable and convincing display of power, and the mockers would be back-peddling pretty fast. But in the full Christian sense, would they believe in him? Of course not! To believe in Jesus in the Christian sense means not less than trusting him utterly as the One who has borne our sin in his own body on the tree, as the One whose life and death and resurrection, offered up in our place, has reconciled us to God. If Jesus had leapt off the cross, the mockers and other onlookers could not have believed in Jesus in that sense, because he would not have sacrificed himself for us, so there would be nothing to trust, except our futile and empty self-righteousness.
But then Carson explores in deeper depth the meaning of their statement, “He saved others but he can’t save himself.”
The deeper irony is that, in a way they did not understand, they were speaking the truth. If he had saved himself, he could not have saved others; the only way he could save others was precisely by not saving himself. In the irony behind the irony that the mockers intended, they spoke the truth they themselves did not see. The man who can’t save himself—saves others.
One of the reasons they were so blind is that they thought in terms of merely physical restraints. When they said “he can’t save himself,” they meant that the nails held him there, the soldiers prevented any possibility of rescue, his powerlessness and weakness guaranteed his death. For them, the words “he can’t save himself” expressed a physical impossibility. But those who know who Jesus is are fully aware that nails and soldiers cannot stand in the way of Emmanuel. The truth of the matter is that Jesus could not save himself, not because of any physical constraint, but because of a moral imperative. He came to do his Father’s will, and he would not be deflected from it. The One who cries in anguish in the garden of Gethsemane, “Not my will, but yours be done,” is under such a divine moral imperative from his heavenly Father that disobedience is finally unthinkable. It was not nails that held Jesus to that wretched cross; it was his unqualified resolution, out of love for his Father, to do his Father’s will—and, within that framework, it was his love for sinners like me. He really could not save himself.