The man who is utterly powerless is powerful (Matt 27:32-40). Matthew provides ample evidence to demonstrate just how weak and powerless Jesus is. Victims were crucified completely naked: the cross was meant to be an instrument of shame as well as of pain. So the soldiers gamble to determine who will gain possession of Jesus' clothing. As the soldiers keep watch, Jesus has no hope, none whatsoever, of rescue. Then comes the mockery that shows the significance of these evidences of Jesus' weakness and powerlessness. If we are going to understand why Matthew reports these words, we must remember that the theme of Jesus' destruction of the temple has already been introduced—he had said he would destroy the temple and rebuild it in three days.
Jesus claimed so much power; now witness his powerlessness. So in light of his claim, they say "save yourself"—which of course they utter ironically, since they are convinced he his helpless and cannot do a thing to help himself. Jesus' claims are somewhere between ridiculous and scandalous—and they deserve to be mocked.
But the apostles know, and the readers of the Gospels know, and God knows, that Jesus’ demonstration of power is displayed precisely in the weakness of the cross. Because we read John’s Gospel, especially John 2, we know what Jesus actually said on this subject: “Destroy this temple, and I will raise it again in three days” (2:19). According to John, Jesus’ opponents did not have a clue what he meant; indeed, Jesus’ own disciples had no idea, at the time, what he meant. But after Jesus was raised from the dead, John says, the disciples remembered his words; they believed the Scripture and the words Jesus had spoken. They knew he was talking about his body (vv. 20–22). The point is that under the terms of the old covenant, the temple was the great meeting-place between a holy God and his sinful people. This was the place of sacrifice, the place of atonement for sin. But this side of the cross, where Jesus by his sacrifice pays for our sin, Jesus himself becomes the great meeting-place between a holy God and his sinful people; thus he becomes the temple, the meeting-place between God and his people. It is not as if Jesus in his incarnation adequately serves as the temple of God. That is a huge mistake. Jesus says, “Destroy this temple, and in three days I will raise it up.” It is in Jesus’ death, in his destruction, and in his resurrection three days later, that Jesus meets our needs and reconciles us to God, becoming the temple, the supreme meeting-place between God and sinners. To use Paul’s language, we do not simply preach Christ; rather, we preach Christ crucified.
Excerpt modified from Scandalous: The Cross and Resurrection of Jesus by D.A. Carson.