One of Torrey's major works was
The Jewish Foundation of Islam (1933), where he suggests that
Muhammad based Islam and the Quran, not on Christianity as was (and is) generally believed, but on a Semitic faith that goes back to
Ismael, and on strong Jewish bases. He notably held that the
Ramadan month patterned the Christian fast of Lent, but that, as Muhammad knew little about Christianity, he only knew the Jewish way of fasting and imposed it to his believers. This hypothesis is rather weak (as it does not justify why that specific month was chosen, and there are other major differences) and was strongly criticized in later scholarship. In general in can be summarized that, in Torrey's opinion, Islam as created by Muhammad was based on Jewish and Pagan bases, but contained a definite Christian element as well. Most of the foundation of Islam, however, he holds to be built on Jewish bases. To him, the presence of important Jewish colonies in Arabia is due to massive migration of Israelites from the North. Torrey also believes that the Muslim
ablution practices were based on Jewish customs. Torrey held that "in the Koran itself there is no clear evidence that Mohammed had ever received instruction from a Christian teacher, while many facts testify emphatically to the contrary; and [...] on the other hand, the evidence that he gained his Christian material either from Jews in Mekka, or from what was well known and handed about in the Arabian cities, is clear, consistent, and convincing." And that: "He lived among Israelites, and knew much about them." These opinions are still debated and, while Torrey's works have definitely weighed on scientific knowledge, scholarship still has not reached a united conviction on these topics. However, Torrey's arguments on the fact that reading and writing were much more common in the
Hijaz that usually thought are confirmed by archaeology of the region in the 20th and 21st centuries, where thousands of inscriptions in Safaitic, Arabic and Nabateo-Arabic were found. ==Books ==