The crucifixion is the center point of the Christian faith, and there's a lot going on in the story today. Not only is Jesus fulfilling scripture and resolving the gap between God and man, but many of the human players are revealing their true selves as well. When the religious leaders decree, "we have no king but Caesar," they actually aren't speaking the truth. Caesar isn't their king, but neither is God. They have rejected both. That only leaves themselves, and that certainly appears to be the one ruling them at the moment.