Mark 15:32

Let the Christ, the King of Israel, now come down from the cross, that we may see and believe. And they that were crucified with him reproached him.

That we may see and believe ... Well, why did not Christ do it? Simply because it was impossible; not for Christ, of course, for he could have descended from the cross at the expense of his message of salvation; but it was impossible that such a thing, even if Jesus had done it, would have had the slightest effect on the priests. There was no miracle which God might have performed which could have changed a hypocritical Pharisee into a loving follower of Jesus. The Lord did a far more wonderful thing than merely coming down from the cross, when, three days later, he rose from the dead. Even then, however, he did not appear to them. It would have done them no good at all.

They that were crucified with him reproached him ... This is a reference to the early part of the crucifixion scene, at which time both the robbers reproached Jesus. In a little while, however, the nobler robber lovingly invoked Jesus' blessing and received it.