The Qur'an in Context

To a contemporary audience, research of the kind undertaken by Speyer easily appears as obsessed with the notion that to understand a text is equivalent to unearthing its 'sources.' While such an approach is already frowned upon when applied, for example, to the Bible or to ancient Greek and Latin literature, with regard to the Qur'an it is often suspected of serving an underlying political agenda as well, namely, of aiming to demonstrate that the Qur'an is nothing but a rehash of earlier traditions in order to discredit the Islamic faith and assert Western cultural superiority. [9] 

And it is true that the title of Geiger's study--"What did Muhammad borrow from Judaism?" -- does seem to bear out such misgivings: Muhammad, it is implied. 'borrowed' existing religious concepts and motives--or, worse, he borrowed and misunderstood them -- and passed them on to his followers. An obvious suspicion about the line of research initiated by Geiger would thus be that in his eagerness to demonstrate the Jewish origin of many Qur'anic conceptions, he is prone to overlook the substantial modifications these have undergone on the way, or to dismiss such modifications are mere 'misunderstandings' rather than functionally meaningful transformations. 

Nicolai Sinai and Angelika Neuwirth, "Introduction" in The Qurʼān in context: historical and literary investigations into the Qurʼānic milieu / edited by Angelika Neuwirth, Nicolai Sinai, Michael Marx (Leiden: Brill, 2010), 4.