Crusades at wikipedia:
http://en.wikipedia.org/wiki/Crusade
"The Crusades were a series of several military campaigns—usually sanctioned by the Papacy—that took place during the 11th through 13th centuries. Originally, they were
Roman Catholic endeavors to recapture Jerusalem and
the Holy Land from the Muslims, but some were directed against other Europeans, such as the Fourth Crusade against Constantinople, the Albigensian Crusade against the Cathars of southern France and the Northern Crusades."
I don't have much time for anything else, I'll be back to answer questions later.
P.S. What I'm saying is most of this war, with which both nations(or religions or whathaveyou) have harbored bad feelings for the other for a while, was mostly born out of conflict for the so-called "Holy land", and the extensions thereof. I don't see how you could argue that this is historically untrue. PPS Jews were mistreated by christians too. In fact, where do you think anti-semitism in europe came from? Very much a religious war.