Ok... So I Was Listening to NPR This Morning

...And the following thought occured to me:

Why is there a civil war in Iraq? Really. I'm totally serious with this question. I have no idea why they are fighting.
*

I mean, sure, I understand that some of them are Sunnis and some of them are Shiites, but why are they fighting? That's no reason to kill one another, is it? I don't get it. To me, what is important in my country is politics: where does the money go; what freedoms am I allowed; what medical research do we do; how secure are we, etc. But the Iraqis don't seem to be fighting about politics; they seem to be fighting about... What? Seriously. Does anyone have an answer to this question?
It seems to me that Iraq and Democracy don't really go very well together. There is a scene from David Lean's gorgeously-painted Lawrence of Arabia that attempted to illustrate this in 1962 that I think about a lot when I hear reports from the Arab world nowadays. In it, a group of Arab warlords tries to come to a compromise and eject Westerners from their land. It doesn't work. They can't expel the British from their lands because they can't agree with one another. The meeting ends only in frustration. A gun goes off (as I recall) and everyone leaves pissed. The (Western) hero Lawrence is left, head-in-hands, alone in the meeting room.

If they're fighting about religion, then that's just stupid. In this country we fight about religion, too, but here we do it by yelling at one another, not by killing children. If someone knows of another reason that they're fighting, please tell me, because I just get more and more confused.