The relation of Islam to the other religions has been established by God in His revelation, the Qur’an. No Muslim therefore may deny it; since for him the Qur’an is the ultimate religious authority. Muslims regard the Qur’an as God’s own word verbatim, the final and definitive revelation of His will for all space and time, for all mankind. The only kind of contention possible for the Muslim is that of exegetical variation. But in this realm, the scope of variation is limited in two directions. First, continuity of Muslim practice throughout the centuries constitutes an irrefutable testament to the meanings attributed to the Qur’anic verses. Second, the methodology of Muslim orthodoxy in exegesis rests on the principle that Arabic lexicography, grammar, and syntax, which have remained frozen and in perpetual use by the millions ever since their crystallization in the Qur’an leave no contention without solution. These facts explain the universality with which the Qur’anic principles were understood and observed, despite the widest possible variety of ethnic cultures, languages, races, and customs characterizing the Muslim world, from Morocco to Indonesia, and from Russia and the Balkans to the heart of Africa.