Why did crusaders risk their lives for Jerusalem?

The justification for the crusades began in 1009, when the Fatimid caliph of Cairo had the Church of the Holy Sepulchre in Jerusalem destroyed. His successor permitted the Byzantine Empire to rebuild it under stringent circumstances, and pilgrimage was again permitted, but many stories began to be circulated in the West about the alleged cruelty of Muslims toward Christian pilgrims. The reasons, for individuals risking their own lives in the crusades, are varied. At the time, there was an awakening of intense Christian piety and public interest in religious affairs, providing overwhelming popular support for the crusades. Some crusaders were motivated by a belief that they were doing the work of God. Others were motivated by a sense of adventure, or just an opportunity to escape their humdrum existences. Many hoped for the booty that was expected to come with military success.