Well, I don't believe in the divinity of Christ. Nor do I even really believe that the Biblical Jesus existed. But I was still moved.
I think that what is truly moving is the HEROIC IDEAL being displayed in the film - that a man (whether myth or reality) deliberately CHOSE to undergo horrible torture so as to redeem mankind. Remember, according to the myth, Jesus could have walked away at any moment (via angelic intervention). According to the myth, Satan was stalking him, using his own people against him, bringing the full weight of torment upon him. It's not so much the torture that he underwent as the fact that he completely and deliberately decided to endure it based upon the principle of love. That's why Christians (whether full-fledged or just vaguely, as in my own case) are moved by the film, because we wish to imitate that same spirit of self-sacrifice and endurance for the sake of others.
At every moment, Christ could have walked away, said, This is enough, screw these ungrateful people, I'm outtie. And left us to rot in Hell for all eternity. But he refused to do so, and gladly grasped his Cross. It helps us to endure our own crosses - thinking that if God permits something to happen, we can not only endure it, we can force the evil we endure to create a newer and lasting Goodness. That's why the film is so powerful for Christians - why it moves us to try to make our lives, our worlds, better around us.
Schindler's list is very powerful, too, but for a different reason. The victims in Schindler's List had no choice - they were helpless victims of Nazi tyranny. So it might move us to try to prevent such abuse of power in the future - but it does not have the same powerful effect on a individual Christian in his own life, although it might affect the political decisions he makes or the things he chooses to support (like the right of Israel to exist, or the prevention of mass executions in Iraq, or the intervention in Kosovo).
Schindler's List is a powerful argument against racism, against mindless support of power, against the language of fear - but the Passion is a powerful argument FOR love, FOR self-sacrifice, FOR endurance and compassion.
CZAR