The Christians and Muslims each saw the other as heretics who were leading people down a path to damnation. During Muslim rule, Christians and Jews suffered persecution for being “people of the book” and were taxed due to a canonical tax found in the Qur’an called the poll-tax. This was to be imposed on “the people of the book” and eventually evolved into the seizing of Christian monasteries, churches, and schools. Christians saw this as punishment for their sin and some believed Muslim rule was a sign of the apocalypse. Christians, in response to their treatment and their view of Islam as sinful due to its practices of polygamy and supposed devotion to carnality, wrote polemical books criticizing Islam for being polytheistic and idolatrous although this was completely untrue. Even in later centuries when Christians knew much more about Islam they continued to write the same criticisms regardless of the extent of their knowledge of what true Islam was. These gave way to the crusades. The idea for the crusades originated in the belief that Christian must defend the church from heretics and threatening non-Christians. Additionally, the president had already been set by both Pope Leo VI and Pop John VIII that they could call upon armies to defend the church on a religious basis.

Pope Urban II, in a sermon tells the people about the seven battles in which Muslim rule had been established and urges them to fight for the freedom of their fellow Christians and even says “On this account I, or rather the Lord, beseech you as Christ’s heralds to publish this everywhere and to persuade all people of whatever rank……to carry aid promptly to those Christians and to destroy that vile race from the lands of our friends” (Anderson and Bellenger, 89). His use of God as motivation was enough to persuade Christians to enter into a crusade for the freedom of other Christians. Pope Urban II also tells the people that the grave of Jesus had been taken over by “unclean peoples” (90). Lastly he cites lines from a gospel which promise people who have given up their families and their possessions in the name of god will receive “everlasting life” (91). Although he does not promise it, the Pope intends that all who heard him speak would believe that following this gospel was a sure way to secure a space in heaven for themselves.

In the Stephen of Blois letter, again and again the successes of the soldiers are attributed to God and every action they have taken is called holy. The same occurs in The Conquest of Lisbon, each portrays the religious fervor with which the men were supposed to be fighting with, even if, as it says in the preface to Stephen’s letter, the men did not actually feel this impassioned. In The Conquest of Lisbon, Psalms and several gospels are quoted which again show that the crusaders are meant to be on a holy mission only for the purpose of god and of freeing their fellow Christians regardless of the harm that might come to themselves or the riches they may or may not acquire along the way.