This is a surprisingly good film (when it came out, I heard that it was rubbish) about the Crusades, specifically the fall of the Crusader Kingdom of Jerusalem. Typically, they've messed around with history a bit... Orlando Bloom plays Balian the blacksmith-turned-knight who realises the futility of it all.
Here's one of the best dialogues in the film (from about 1 hour 40 mins in):
[Bishop] How are we to defend Jerusalem without knights? We have no knights.
(Balian looks around, and finds a teenage lad.)
[Balian] What is your condition?
[lad] I am servant to the Patriarch.
[Bishop] He's one of my servants
[Balian] Is he?
[Balian] You were born a servant. Kneel.
[Balian] Every man at arms or capable of bearing them, kneel! On your knees!
[Balian] Be without fear in the face of your enemies. Be brave and upright, that God may love thee. Speak the truth, even if it leads to your death. Safeguard the helpless. That is your oath.... Rise a knight. Rise a knight.
[Bishop] Who do you think you are? Will you alter the world? Does making a man a knight make him a better fighter?
That dialogue has great potential for talking about what the priesthood of all believers (for example) means...
There's lots of other interesting stuff in the film, like questions about who is a Christian and who isn't, and what it means for an earthly place to be called the "Kingdom of Heaven", as well as the importance or otherwise of the earthly Jerusalem. Can't say I agree with them on everything of course, though there are some good points made and it's interesting nevertheless...
In terms of the politics, people generally seem to agree that it's fair to everyone. There are good and bad people on the "Christian" side, there are wise and stupid Muslims (though I can't think of any Muslim characters who were bad in the way that some of the "Christian" nobles were, but on the other hand there are only a few Muslim characters who really get developed...).