Final answer:
Western Christians were motivated to join the Crusades mainly by religious fervor and the promise of spiritual rewards, though some sought wealth, land, and adventure. These motivations were underpinned by the desire to reclaim the Holy Land and offer penance for sins. Jerusalem's sacred status to Abrahamic faiths and the complexities of the movement, including the later decline driven by geopolitical shifts and the growth of European nation-states, contribute to our understanding of the Crusades.
Step-by-step explanation:
The motivations of western Christians for participating in the Crusades were multifaceted. While some were inspired by the pursuit of wealth and land, the overarching motive was deeply rooted in religious fervor and the promise of spiritual rewards. Pope Urban II's call for the First Crusade was driven by a desire to reclaim the Holy Land from Muslim control and offer full penance for the sins of those who took up the cross. The concept of religiously motivated warfare was not unique to Christianity, as it also existed in Islam. The reasons Western Christians traveled to the Middle East as crusaders ranged from securing political power to gaining economic dominance through trade expansion, and some crusaders were also motivated by the adventure and potential glory.
Religiously, Jerusalem was of immense importance to all Abrahamic faiths, inciting fervent desire among different groups to control the sacred city. Many eastern Christians and Jewish people did not welcome the arrival of the crusaders into the Holy Land due to the atrocities and betrayals committed, including the massacre of innocents, demonstrating the complexity of the Crusading movement through its failure to uphold its own ideals. The decline in crusading in the later Middle Ages was linked to the decline of the popes' power and influence, geopolitical shifts, the growth of nation-states, and a changing focus among European monarchs.