Why would people fight for the catholic church during the crusades

The two main reasons for people to fight in crusades are reasons of faith and monetary reasons. People believed they would free the Holy Land from heathens during their campaigns. Since a fundamental catholic believe is that “good” deeds in this life have a positive impact on the next life, that begins after death, many crusaders surely believed that their actions had a positive impact on their own next life. Apart from reasons of faith there have also been monetary incentives. People could usually take all the riches they plundered on their crusades back home and nobles were often rewarded with vast amounts of land, while their lands at home were given guaranteed protection by the king from invasions of any of the nobles rivals.

Is there a passage that comes with this question or should i know this right off the bat, because if it is, i probably have short term memory loss or college is too stressful