"this crusade, this war on terrorism, is going to take awhile." - GW Bush[1].
"President Bush said to all of us: 'I am driven with a mission from God'. God would tell me, 'George go and fight these terrorists in Afghanistan'. And I did. And then God would tell me 'George, go and end the tyranny in Iraq'. And I did."[2]
It's pretty easy to paint a picture of attempted cultural (if not religious) domination by the West even without quotes like that. Add that stuff in and it is harder to explain how it isn't the same.
Let's suppose you've managed, as a family, to hack and slash your way to the top of the nobility. Grandfather was a friend of the guy who became king, father inherited lands and got them productive, and now five brothers have all survived. The eldest gets the land. The next four have learned to ride horses, swing swords, and wear armor. One of them decides that the Church isn't so bad, and thus effectively goes into politics. There are still 3 armed badasses who won't be getting the power and wealth they are used to... unless they go and take it from someone else.
Their brothers in the Church have an idea: maybe you can go be violent somewhere else?