What purposes did these medieval Christian constructions of Islam serve? Christians increasingly saw in Islam a formidable threat to Christianity's claims of superiority and hegemony in Europe and beyond. Faced with the Muslim world's competing theological claims, impressive military accomplishments, expanding empire, and superior intellectual and scientific advancements, medieval Christian authors responded polemically and aggressively. In the context of the Crusades and the Reconquista, theologians depicted Islam initially as idolatry and ultimately as heresy in order to justify violence and aggression against Muslims. In those circumstances in which Christians lived under Muslim rule, these same depictions were aimed at providing Christian dhimmis with the ideological tools to resist converting to Islam or, in the case of ninth-century Cordoba, to embrace martyrdom. By the end of the Middle Ages, centuries of military aggression, political hostility, and anti-Muslim discourse had taken their toll. Muslims became the feared "Other" in the European Christian imagination.

XREF: This connects with Edward Said's Orientalism and the broader construction of a feared 'Other' in European identity — the colonial framing has medieval roots here.

Green, Todd H, The Fear of Islam_ An Intro…, loc. 139