As a cult Islam centralizes and ossifies. There is precious little 'diversity' within Islam present or past. If Moslems are faithful to the Koran there is the absolute despotic merger of church and state; a denial of free will and freedom; and a slavish devotion to Muhammadan text. Apparently 'total systems' do not create the dynamism necessary to propel society forward. A cursory reading of history makes that clear.
Medieval Christianity, which was in part [and only in part], an era of hardship, plague, incessant wars, exogenous threats from Moslems, Avars, Vikings and others and indeed Church corruption; was nonetheless, the only society in world history which divided church from the state [contrary to myth there was never a merger of church and state]; elevated reason, free-will and responsibility; and demanded progress and a better social order to protect the weak and dispossessed. Not one single iota of proof exists, that Islam for instance, past or present, developed any of the above pre-requisites for modernity. The gold-standard for academics cited as an 'advanced state' of Moslem-Christian rose-petal tossing inter-faith hugging is 12thcentury Sicily under Robert II – a Normanized, re-Christianized island, dead in the middle of trade routes. This Norman-premised 'utopia' lasted one generation and had nothing whatsoever to do with Islam. It was a Christian state, hence its success.
Plurality developed only in Medieval Europe after the dead-weight of the Roman empire, itself an obstruction to civilization, thankfully collapsed. With the disease of Rome now cured from the European body-politic, civilization could arise. What is striking about Medieval Christian Europe is the creative tensions induced by a dynamic society. This is real diversity. The diverse attitudes, skills, political preferences, ideas and networks of a society on the move. Not the diversity of skin-color, or last names that giggling post-modernists are so fond of.
Creative tensions in medieval society and politics led to innovation and development in every sphere of the political-economy. They also led to the rise of new religious orders and forms of spirituality, many good, some weird, but with many reforming, improving and sustaining society. Hospitals, hospices, welfare and indigent care were all medieval inventions. Even public schools developed during the time of Charlemagne, were becoming common. The idea of helping those in need, or educating your family, did not exist outside of certain Jewish strictures, until the ministry of Christ. Succor and education were two great gifts of Christianity. In this vein monastic orders which dominated education and literacy, were rampant appealing to both metaphysics and rationality. New ideas also emerged in popular religion for instance during the struggle between orthodox Christianity and numerous heresies found in the 13th century.
The plurality in tensions and beliefs gave rise to two important Medieval innovations. The first was political plurality which was essential to create wealth. In England, Holland, Italy and elsewhere, the state had to share power with the Church, guilds, barons and the burgeoning merchant-bourgeoisie. Autarchic despotism was impossible. There is ample evidence that people would simply leave an inhospitable state and move to a political unit promising more freedom, mobility and safety. Political fragmentation ensured competition. Monastic houses incorporated firms as early as the 10th century. Trade routes lengthened and became more complex. Wealth, so necessary for the development of higher living standards and the creation of productivity enhancing technology took off after the 9th century.
A second manifestation of tensions expressed in ideas and freedom is the creation of Universities. During the 12th and 13th centuries, universities were built in every major European city. These universities met the demand for education in the liberal arts, of which 7 were emphasized, namely: grammar, rhetoric, logic, astronomy, geometry, arithmetic, and music. Education in a variety of topics was deemed by the Medieval mind, to be a central feature of prosperity. Many universities had specialties with law the central focus at Bologna, medicine at Salerno, and theology and philosophy at Paris. Each university thus attracted 'experts' stimulated debate in their chosen specialty, and changed attitudes in the culture at large.
The university system in the 12th century developed what is commonly called 'Scholasticism', or systems of logic which incorporated some aspects of Greek and Roman thought with Christianity. Many medieval scholars such as Anselm of Canterbury, placed faith before reason. Others, such as Peter Abelard, put reason first. The great 13th-century Dominican philosopher Thomas Aquinas produced a brilliant synthesis of faith and reason. Other scholars mused over whether vernacular language could even adequately describe either faith or reason. By the time of Roger Bacon [d. 1294], the scientific method had been established along with many of the basics of higher math and science.
This ferment of the mind, elaborated upon by a vibrant and partially Church-funded university system had a broad societal impact. People's attitudes and minds were profoundly changed. Visionaries and reformers initiated powerful and profoundly spiritual orders such as the Cistercians, Franciscans, and Dominicans. Saint Francis of Assisi, imitating Christ, rejected the urban wealth of his family and fled civilization. The Franciscans were a beggar-order for men, and very quickly a similar order for women was incorporated – the Poor Clares. Christian Neoplatonism, a synthesis of Plato’s ideals and Christian mysticism held sway during the 12th and 13th centuries. Aristotle – who was mostly wrong – and his idea of the material being the only reality, was rejected. Bonaventure, a Franciscan who lived from 1221 to 1274, developed a mystical philosophy guiding Christians toward contemplation of the ideal realm of God.
In short, only in Medieval Christian Europe do we see the dynamic plurality in governance, markets, religion and society so necessary in the creation of the modern world.