What motivated Christian soldiers to fight the crusaders

The "enemies" of the Church in Europe included people who were not Christians. It also included Christians who were labeled heretics, that is, people who challenged the official teachings of the Church or who questioned the pope's power and authority.

Millions of people, Christian and non-Christian, soldiers and noncombatants lost their lives during the Crusades. In addition to the enormous loss of life, the debt incurred and other economic costs associated with the multiple excursions to the Middle East impacted all levels of society, from individual families and villages, to budding nation-states. The wars also resulted in the destruction of cities and towns that lay in the crusaders' wake. In his Decline and Fall of the Roman Empire, Edward Gibbon refers to the Crusades as an event in which "the lives and labours of millions, which were buried in the East, would have been more profitably employed in the improvement of their native country."