Prior to the Crusades Musims viewed Europeans as aggressive barbarians, their few contacts generally involving military conflicts. So initially they did not perceived the crusaders as much of an adversary. But the Crusaders struck during a time of disarray while the Caliphates were in decline and following the death of several important leaders. Christian occupation and atrocities in the Levant caused greater resentment but increased diplomacy lead to more realistic perspective of Europeans. The Muslim world never really recovered and still holds resentment toward Europeans.
—David Foss