In defending Islam to the West, it’s common to hold up early Islamic culture as far superior to the Christian cultures of the time for its advances, its supposed tolerance, and so on; the usual implied message is, “Islam isn’t as bad as you think it is, or else it couldn’t have produced all these great things!” The principle is sound—it’s basically the same one articulated by Jesus when he told his disciples, “A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Thus you will know them by their fruits.”
The only problem is that the picture we’re usually given is significantly askew from the historical reality. As Robert Spencer put it in Jihad Watch,
The idea that Islamic culture was once a beacon of learning and enlightenment is a commonly held myth. In fact, much of this has been exaggerated, often for quite transparent apologetic motives. The astrolabe was developed, if not perfected, long before Muhammad was born. The zero, which is often attributed to Muslims, and what we know today as “Arabic numerals” did not originate in Arabia, but in pre-Islamic India. Aristotle’s work was preserved in Arabic not initially by Muslims at all, but by Christians such as the fifth century priest Probus of Antioch, who introduced Aristotle to the Arabic-speaking world. Another Christian, Huneyn ibn-Ishaq (809-873), translated many works by Aristotle, Galen, Plato and Hippocrates into Syriac. His son then translated them into Arabic. The Syrian Christian Yahya ibn ‘Adi (893-974) also translated works of philosophy into Arabic, and wrote one of his own, The Reformation of Morals. His student, another Christian named Abu ‘Ali ‘Isa ibn Zur’a (943-1008), also translated Aristotle and others from Syriac into Arabic. The first Arabic-language medical treatise was written by a Christian priest and translated into Arabic by a Jewish doctor in 683. The first hospital was founded in Baghdad during the Abbasid caliphate—not by a Muslim, but a Nestorian Christian. A pioneering medical school was founded at Gundeshapur in Persia—by Assyrian Christians.
In sum, there was a time when it was indeed true that Islamic culture was more advanced than that of Europeans, but that superiority corresponds exactly to the period when Muslims were able to draw on and advance the achievements of Byzantine and other civilizations. But when the Muslim overlords had taken what they could from their subject peoples, and the Jewish and Christian communities had been stripped of their material and intellectual wealth and thoroughly subdued, Islam went into a period of intellectual decline from which it has not yet recovered.