What are some of the reasons why the Christian West attacked the Muslim East?

The Catholic Church called for the Crusades to liberate the Holy Land and Jerusalem from Muslim rule, an unacceptable situation to the eyes of Christian Europe because Muslims were treated as infidels. The Vatican offered forgiveness of sins and eternal life to all those who participated in the holy war against the infidels. Beyond the religious motives, many European feudal lords and powerful kings saw a chance to conquer land, wealth and position in the Middle East, a material interest that was also a powerful drive of the Crusades.