As mentioned in another thread, I just started reading a relatively new book on the First Crusade, and in the first chapters the author, Thomas Asbridge (Queen Mary Uni, London) develops a few interesting thoughts on the genesis of the crusade and especially on the motives of the Papacy, Pope Urban II, to proclaim it.
He argues that Urban, far from being worried about the Muslim occupation of the Holy Land or the treatment of Christian pilgrims therein, and probably even less about the endangered Byzantine Empire and its slightly heretic Christians, pursued a consequent policy to strengthen the Papal power and influence that until his immediate predeccessor Gergory had hardly strechted outside the confines of Rome.
Asbridge argues further that Urban attempted to achieve this by bringing the European rulers and feudal lords into a moral dependency to the Papacy: firstly by finally concluding the process of "sanctifying violence", by authorising the employment of war and by reserving his right for such authorisation. It thus meant that a fundamentally pacifist Christianity ( see sermon on the mount) had finally changed into one that accepted violence as means and therefore could wage a "Holy War" .
Secondly by channeling the most violent forces of an inherently violent medieval society, namely the feudal lords of Europe, into an authorised and accepted outlet to release such violence, thereby offering salvation and relief from guilt that the good Christian knights of Europe had carried before when they had simply massacred each other or the peasantry.
Fighting wars, from being sinful, now offered a heavenly reward.
Interesting ideas on the intellectual preparations for the Crusades, nothing absolutely new, and is Asbridge's detection of a remarkable shift in Christianity's self-understanding justified?
Thomas Asbridge
The First Crusade, A New History
OUP