Case in point, the Crusades. Yes, I oversimplified, but I figured you'd get the concept. Apparently you'd rather nitpick than see that a major war(or set of wars, rather) were sparked off, because the Pope... heck, I never really paid that much attention. I forget the exact reasons... but I'm pretty sure slaughtering people for the sake of a religion that clearly states "Thou shalt not kill" is pretty much considered "evil," by most standards.
Yeah, you don't know a damn thing about the Crusades. First of all, the Crusades were not limited to only the Middle East. The Catholic Church called for crusades within Europe as well. In 1063, the Spanish and Portugese were blessed by Pope Alexander II in their wars against the Moors. To my knowledge, there were two crusades that occurred in Europe: the Albigensian Crusade and the Northern Crusades. They were both aimed at eliminating the "heretical" elements still present in France and northeastern Europe.
The general public in the late eleventh century enjoyed an increase in piety. It was likely the result of the Investiture Controversy, which was an ongoing conflict between the Holy Roman Empire and the Papacy over who would control the appointment of church officials. Both sides needed the support of public opinion, and that's how the everyday guy got wrapped in religion so intensely.
The cause of the First Crusade in the Middle East was the Byzantine Empire's defeat at the hands of the Seljuk Turks in 1073. the Empire's territory was drastically lessened as a result of the battle. In 1074, Pope Gregoy VII called for "soldiers of Christ" to help the Byzantine Empire. This call was not very successful.
During the Council of Piacenza in March of 1095, Emperor Alexius I Comnenus sends emissaries to ask Pope Urban II for aid against the Seljuk Turks. The proposal is well accepted in the council. Urban II saw this as an oppurtunity to reunite the Catholic Church and the Orthodox church, which had been split by the Great Schism in 1054. The call for the First Crusade was given at the Council of Clermont in November of the same year.
Of course, the capturing of Jerusalem was a big selling point of the First Crusade, but it was not pure religious zealotry that triggered the Crusades.