Although twelfth-century writers such as Petrus Alfonsi and Peter the Venerable of Cluny attacked Muslim ideas about Jesus and Mary, polemical authors of the thirteenth and fourteenth centuries sometimes presented the same ideas in a positive light, describing the Muslim as a �witness� to the Jews of the truth of Christian ideas. In texts by the Dominican Ramon Martí, the Qur,an itself serves as a �proof� of Christian doctrines about Jesus and Mary and in texts such as the Mostrador de (...) justicia of Abner de Burgos/Alfonso de Valladolid, Muslims are described as �Naza - renes.� The study of these images allows us to distinguish between the representation of Muslims in anti-Jewish and anti-Islamic texts. This article proposes that the representation in anti-Jewish texts was more determined by the norms of those texts than by the ideas about Islamic sources contemporary anti-Muslim writing itself. (shrink)