Why We Fight
I have heard many people say religion is the cause of most wars, and there is some truth to that but not very much. Most wars originate over resources or for profit. Religion (or more accurately, idealogy) is often used to justify war.
For example, it is obvious to almost everyone in the world except some americans that the US is in Afganistan and Iraq because of oil. We claim that we are in Afganistan out of self-defense. However, it would be much cheaper and more effective to retaliate against Al Qaeda covertly than by invading Afganistan. However, 9/11 presented the US with an an opportunity to invade Afganistan, a strategic country in regard to the transport of oil and natural gas from Central Asia to the Arabian sea. That's why the Solviet Union spent nearly 10 years trying to occupy Afganistan. Now it didn't take much to convince US citizens that we should attack Afganistan because most of them probably felt a need for retaliation after 9/11. So in order to justify killing thousands of innocent Afganistan people in order get Osama Bin Laden, all that was needed was a documentary (which was shown on TV about shortly before the US attacked Afganistan) on how the Taliban treat women. The average american watching that documentary was probably thinking something like this: "Look at the way those bastard Taliban treat their women -- they deserve to have their asses kicked". So note that the idealogy of women rights was used to justify an attack against Afganistan -- not religion.
Now Iraq has the second largest oil reserves in the world, second only to Saudi Arabia. And that is what we are there for. A lot of reasons were used to justify the war in Iraq and among them were the promotion of freedom and democracy. Note that freedom and democracy are american idealogies and not religion.
US oil companies, weapons developers, and Haliburton are making a lot of money over these wars while the average US citizen is dupped by an extensive propaganda campaign into believing that the US cause is to spread freedom and democracy by gun point is noble.