Final answer:
Pope Urban II called for the First Crusade primarily to liberate the Christian Holy Land and defend Christians in the Middle East. He also sought to unify the church and test his influence against European political rivals. Material incentives, religious fervor, and the concept of holy war also played a significant role in motivating western Christians to become crusaders.
Step-by-step explanation:
Reasons and Motives for the First Crusade
Pope Urban II had several reasons for calling Christians to participate in the Crusades. The primary motive was the defense and liberation of the Christian Holy Land. Urban II was responding to a request for aid from the Byzantine Empire and sought to support Christians in the Middle East. In his speeches, Urban II emphasized the spiritual benefits, invoking tales of past Christian victories and the perceived persecution under Turkic control, calling for an 'armed pilgrimage' to reclaim Jerusalem.
Urban II also aimed at religious reform and church unity, with the Crusades serving as a test of the pope's influence over the Christian population, which would aid in his contest for power against political rivals within Europe, including the German emperors. Additionally, the pope wanted to aid the Byzantine Empire to guard the frontiers of Christianity, especially since he had to compete with a rival pope supported by the German emperor.
The Crusades were a transformative movement for medieval Christendom, becoming a symbol of religiously motivated warfare and setting the stage for future conflicts and lasting negative stereotypes of non-Christians. Both the material incentives, such as indulgences and property protection, and the deep-seated religious fervor motivated western Christians to journey to the Middle East as crusaders.