Absolution of sins is a powerful motivator for many, as is the chance of loot for the italian normans.. The bottom line is the church was fixed on one goal and it wasn't to kill muslims, but heal the schism and unify the faith under the Roman, rather than Orthodox Banner.... The many Jihads prior to the crusades you seem to want to ignore, but the evidence is clear, that europe learned lessons from the arabs and imitation was clear both in the eastward expansion and counter drives into Spain.Here is a list of every major history of the First Crusade, literally every single one of them points to the central role of the Church, let me know which one's you have read or which one's dispute the role of the Chruch. I have read Jhon, Hotaling and Riley-Smith. Happy to take any questions you may have. I'll wait....
- Asbridge, Thomas (2004). The First Crusade: A New History. Oxford. ISBN 0-19-517823-8.
- Asbridge, Thomas (2012). The Crusades: The War for the Holy Land. Simon & Schuster. ISBN 978-1-84983-688-3.
- Curta, Florin (2019). Eastern Europe in the Middle Ages, 500–1300 (two volumes). Brill's Companions to European history No. 19. Leiden: Brill. ISBN 978-90-04-34257-6.
- France, Jhon (1994), Victory in the East: A Military History of the First Crusade, Cambridge University Press, ISBN 9780521589871
- Frankopan, Peter (2012). The First Crusade: The Call from the East. Harvard University Press. ISBN 978-0-674-05994-8.
- Gil, Moshe (1997) [1983]. A History of Palestine, 634–1099. Translated by Ethel Broido. Cambridge: Cambridge University Press. ISBN 0-521-59984-9.
- Harris, Jonathan (2014). Byzantium and the Crusades (2nd ed.). Bloomsbury. ISBN 978-1-78093-767-0.
- Hillenbrand, Carole (1999). The Crusades: Islamic Perspectives. Routledge. ISBN 0-415-92914-8.
- Hindley, Geoffrey (2004). A Brief History of the Crusades: Islam and Christianity in the Struggle for World Supremacy. London: Constable & Robinson. pp. 300. ISBN 978-1-84119-766-1.
- Holt, Peter M. (1989). The Age of the Crusades: The Near East from the Eleventh Century to 1517. Longman. ISBN 0-582-49302-1.
- Holt, Peter Malcolm (2004). The Crusader States and Their Neighbours, 1098-1291. Pearson Longman. ISBN 978-0-582-36931-3.
- Hotaling, Edward (2003). Islam Without Illusions: Its Past, Its Present, and Its Challenge for the Future. Syracuse University Press. ISBN 978-0-8156-0766-3.
- Jotischky, Andrew (2004). Crusading and the Crusader States. Taylor & Francis. ISBN 978-0-582-41851-6.
- Konstam, Angus (2004). Historical Atlas of the Crusades. Mercury Books. ISBN 1-904668-00-3.
- Kontler, László (1999). Millennium in Central Europe: A History of Hungary. Budapest: Atlantisz. ISBN 978-963-9165-37-3.
- Lock, Peter (2006). Routledge Companion to the Crusades. New York: Routledge. ISBN 0-415-39312-4.
- Madden, Thomas (2005). New Concise History of the Crusades. Rowman & Littlefield. ISBN 0-7425-3822-2.
- Montefiore, Simon Sebag (2012). Jerusalem: The Biography. Vintage Books; Reprint Edition (September 18, 2012). ISBN 978-0307280503.
- Neveux, Francois (200
. The Normans. Howard Curtis. Robinson. ISBN 978-1-84529-523-3.
- Nicolle, David (2003). The First Crusade, 1096–99: Conquest of the Holy Land. Osprey Publishing. ISBN 1-84176-515-5.
- Riley-Smith, Jonathan (1991). The First Crusade and the Idea of Crusading. University of Pennsylvania. ISBN 0-8122-1363-7.
- Riley-Smith, Jonathan (2005). The Crusades: A History (2nd ed.). Yale University Press. ISBN 0-8264-7270-2.
- Riley-Smith, Jonathan (199
. The First Crusaders, 1095–1131. Cambridge. ISBN 0-521-64603-0.
- Runciman, S. (1980) [1951]. The First Crusade (abr. vers. of A History of the Crusades ed.). Cambridge University Press. ISBN 0-521-23255-4.
- Tyerman, Christopher (2006). God's War: A New History of the Crusades. Cambridge: Belknap Press of Harvard University Press. ISBN 0-674-02387-0.
- Tyerman, Christopher (2011). The Debate on the Crusades, 1099–2010. Manchester University Press. ISBN 978-0-7190-7320-5.
- Tyerman, Christopher (2019). The World of the Crusades. Yale University Press. ISBN 978-0-300-21739-1.
- Vryonis, Speros (1971). Decline of Medieval Hellenism in Asia Minor and the Process of Islamization in the Eleventh through Fifteenth Centuries. University of California Press. ISBN 0-520-01597-5.
P.S.
The nobles financed themselves, though the church provided monies as loans against land. The Greeks probably provided much of the funding for the actually armed expedition, until after Antioch fell and the crusaders failed to return it.