Matthew 27:42-43 – He saved others; himself he cannot save. If he be the King of Israel, let him now come down from the cross, and we will believe him. He trusted in God; let him deliver him now, if he will have him: for he said, I am the Son of God.
The day Jesus Christ was executed, many scorned Him. Passing by people said all manner of horrible things. They ridiculed Him and chided Him. However, even in their scorn we see the full Truth of the Gospel revealed. As one said in Matthew 27:42-43, He saved others, but He could not save Himself.
The ability of Jesus to save Himself was not based on a limitation of His sovereign power. On the previous night in the garden of Gethsemane, Jesus had chastised Peter for attacking one of the guards sent to take Him. Jesus said at the time that he could command angels to defend Him if needed. However, had He done so, He could not have fulfilled the prophecies concerning Him. (Matthew 26:48-56)
Jesus trusted in God the Father absolutely. The holiness of the Father requires justice and righteousness. We cannot make up for our sins through good works. Sacrifice is required to pay that debt. We might pay the debt in part by dying, but we would simply die being forever lost to the life of God. In order for us to return to Paradise, to have the life intended by the Father, a pure sacrifice was required beyond our ability. The Lamb of God was required to pay the full price. So, Jesus could not come down off from the cross, because He loved us too much.
The one thing these scorners did not count on was the power of God within Him in purity beyond human comprehension. Jesus effectually laid down His life and took it up again having fulfilled the promises of atonement. The grave could not hold Him, and it will not hold any who trust in Him.