To What Extent Was Personal Religious Belief the Dominant Religious Cause of the First Crusade?

To what extent was personal religious belief the dominant religious cause of the First Crusade?

The First Crusade was launched in November 1096 by pope Urban II at the town of Clermont who preached a sermon which ignited Europe into a holy war. Religious motivations were the main reason to go on a crusade along with political motivations and development of knighthood. Personal religious belief played a major part of the first crusade but there were many other factors within religion which played just as an important part.
The main religion in medieval Europe was the Catholic Church branching from East-Byzantine with Greek Orthodox and in the west with Latin Christianity. The fear of hell was immanent and pressing which made anyway people could redeem their sins a necessity. At the time there were only so many ways to be forgiven for your sins which were pilgrimages, donating money and land and crusades which were developed by pope Urban. One of the most famous cases being Fulk Nerra who was a brutal leader of Anjou but also a devout Catholic   who took three pilgrimages at the length of two thousand miles to try and save his soul. On the third pilgrimage was lead naked and whipped begging for forgiveness for the redemption of his soul. This story reflected and shaped the middle ages. Crusades offered opportunity for the sinful knights of Western Europe to cease their endless exploitation of the weak and use of violence to be redeemed. Another personal religious belief held by many in the Middle Ages was that of Eschatological argument which is the idea that the end of the world is immanent. Apocalyptic dread reached its height in 1030 which palpable anxiety helps to explain Fulk’s mentality.
Another personal religious belief held at the time was Indulgence which was developed by Urban II. Indulgence meant that you could forgiveness for your sins by crusading. This could only be used for one sin, but if you were like Fulk and had many sins you would use Plenary...