Essentially, Fletcher's analysis comes down to two main points;
There is no priesthood in Islam. Nor is there, nor can there be, a Church in the sense of a religious institution set apart from the secular world, with its own organization, customs, staffing and handling. Authority within Islam is indivisible; there is no separation between the sacred and the secular. Under a Christian dispensation, on the other hand, there is a distinction between ‘state’, ‘world’, ‘society’ on the one hand and ‘Church’ on the other. The gap between them may be wide or narrow, relations between them warm or wary, but the distinction is always there, always containing the potential for tension and conflict… if there is a line of tension between Church and state (or society) w/in Christendom, which there cannot be under Islam that is going to open up completely different ways of thinking about authority and of organizing the community of the faithful – that is, of conducting politics.
Our word ‘bible’ is derived from the Latin bibliotheca, meaning ‘a library’, and that is exactly what the Bible is. Part of this library comprises a mass of myth, history, law, poetry, counsel and prophecy inherited from Judaism, in aggregate making up the Old Testament.
In the Muslim world, state is church; religion is politics. Thus to conquer (jihad) is to do the will of Allah & thus an insult to (or critique of) the state is an insult/critique of religion. There is no "other" place to flee in Islam if one disagrees with the state or the religion and there is no dissent against the doctrines or principles of the state or the religion. Consequently, if a major critique occurs (such as seemingly did during the era of Averroes and Moses Maimonides) it must be crushed lest it threaten the very pillars of the state/religion. The introduction of Aristotle, which seems to have prompted the nominalist/realist debate in Christendom, must have had a similar effect in the intellectual world of Islam in the 13th century. If a fully complete worldview (such as Aristotle presented) can be derived in a pagan world, without the benefit of the revealed word of Allah, then are our thoughts derived from a divine pattern, or is the divine pattern merely a construct of the human mind? In the West such a discussion raised healthy debate that saw the likes of great minds such as Thomas Aquinas attempting to create a synthesis of the two worldviews. In Islam, the threat of the debate led to the slackening of intellectual curiosity and, as Fatimah Mernisi notes in her analysis, a closing of the Baghdad House of Wisdom, the Bayt al-Hikma, and expulsion of the filasafs (who fled to ... Christendom).
Second, Fletcher notes, Islam does not have the same kind of intellectual discussion as Christianity.
The multiplicity and diversity of Christian texts, and especially of those letters and narratives bearing upon the teachings of Jesus and his earliest followers, have ensured that argument, debate and disagreement have been built into Christian history from its earliest traceable beginnings. From a certain point of view, Christian history has been about the sprouting of different tendencies or sects, about cellular fragmentations and re-formations, played out against a background din of polemic, denunciation and skullduggery. During the early Christian centuries the theological issues were the linked doctrines of the Trinity and the Incarnation, God is One, but He is also Three, the Father, the Son, and the Holy Spirit. …These and related questions, obscure and difficult, exercised the best intellects of the Christian Church during much of the third, fourth and fifth centuries of the Christian era, and are still debated. In answer to them, theological definitions of great – and to the lay mind almost incomprehensible – subtlety were proposed. In some quarters these definitions were accepted; in others rejected.
Doctrinal bickering of this type is not possible under an Islamic dispensation.
The very cursoriness of Rashid’s (al-Dun) ‘venture in occidentalism’, as Bernard Lewis has called it, simply underlines the lack of interest which Islamic scholars took in the West.
In Christendom, by contrast, there was eager interest in the Dar al-Islam. It was an interest which ran in several different channels, now convergent, now separate.
Muslim aloofness from Christendom had the effect of obscuring from view what was afoot… the rise of the West took the world of Islam by surprise. Given Islamic disdain for the West, perhaps it had to happen thus.