That in Medieval Islamic Spain the three cultures of Muslims, Jews, and Catholics lived together in happy harmony is one of the many remarkable falsehoods of today’s widely accepted "knowledge." In Al-Andalus Muslims were in fact at the top of a religiously, racially, and socially stratified society and the sole controllers of the political sphere, with Jews functioning as an ancillary class that had allied itself with the Muslim invaders during their early conquest of Catholic Spain and that for some centuries continued to enjoy an intermediary and at times influential status between Muslims and Catholics.
In fact, in Al-Andalus the majority of the members of "the three cultures" lived in their own neighborhoods, interacting only whenever it was necessary for commercial reasons. Catholics (or "mozarabs," a misleading term, since they were not Arabs in any form or shape, but Catholics who had stayed in Islamic Spain after the Muslim conquest and had kept their religion, customs, and traditions in spite of adverse conditions: in fact, Muslims referred to these Catholics not as "mozarabs," but as dhimmis, that is, a people subject to and "protected"--an ominous term for anyone familiar with protection rackets--by the Islamic hegemonic law) were at the bottom of the totem pole. Many of their churches had been converted to mosques, as had been the practice in all lands conquered by Islam. The best known examples are probably the mosque of Cordoba, built upon an ancient Catholic church (and converted into a Catholic church when Catholics re-conquered Cordoba in the twelfth century), and the great Greek Orthodox church of Hagia Sophia in Constantinople (changed by Muslims to "Istanbul" in the early twentieth century in another well-known procedure whereby the conquerors changed the names of the places they conquered), probably the most beautiful building of the early Middle Ages, turned into a mosque upon the conquest and sacking of Constantinople in 1453 by the Ottoman Kaliph Mehmet II: though now converted into a museum, it still features four minarets that constitute not only a religious desecration but an aesthetic travesty.
It is not true that Muslims shared the Catholic dhimmis' festivities with Catholics (or for that matter, Jewish festivities with Jews). In lands re-conquered by Catholics, but not in Muslim lands (where such temptations did not exist because Catholics were simply forbidden to celebrate publicly their religious holidays), the remaining Muslim population was occasionally tempted to enjoy the merry festivities of Christians, but this always provoked stern rebuttals from the Muslim ulama. These ulama functioned and still function today as the equivalent of a priesthood, another historical myth being that Islam in Spain had not priests. Even today among Muslims the ulama function as priests because they are a source of religious knowledge, preaching, advise, religious injunctions, etc. with no distinction being made between what is religious and what is not, but of course with different rituals, beliefs, organization, etc. than those of Catholic priests: one only has to read the papers to see today the ulama class as a religious clergy in action in Shiite Iran, in Sunni Islamic lands, and even in Western cities. But of course that in Medieval Spain some Muslims wanted to have fun during the Catholic festivities in cities re-conquered and once again controlled by Catholics (again such festivities were forbidden in lands controlled by Islam) constituted no more a sharing of such festivities than when today’s Americans who are not Catholic enjoy Christmas without actually sharing what Christmas means for Catholics, namely the celebration of the incarnation of one of the three personae of God in human form and His birth in Bethlehem–all notions blasphemous to Muslims in Spain.
Catholic dhimmis did not share political power in Muslim Spain, could not hold processions or display publicly the cross or other Christian symbols such as images of Christ, the Virgin Mary, or the saints, they could not ring church bells, their buildings had to be lower than Muslim buildings, they could not ride horses or carry weapons, they had either to convert to Islam or pay a special tax to the Muslim state or die, they could not marry or have sexual intercourse with Muslim women under punishment of death (whereas Muslim men could marry Catholic women and their children must be brought up as Muslims), they could not build new churches (still the case in Muslim states like Saudi Arabia, where building churches is forbidden, and in some other Muslim nations where building churches is extremely difficult or de facto impossible), they had to defer to Muslims socially, and in all legal matters they were subordinate to the Muslim population whenever they came in conflict with it.
The effect of these oppressive social conditions on Catholics was that by the twelfth century Catholics had basically become extinct in Islamic Spain because of flight to the Catholic North, conversions to Islam, and expulsions. Over the centuries, Muslim authorities expelled hundreds of thousands of Catholics to Muslim Africa. Some of these expulsions occurred in retaliation for the armed resistance of the Catholics, among them the famous Omar Ibn Hafsun, who for many years in the mountains of the Sierra Nevada held off the forces of Abd-el-Rahman III (Arab chronicles tell us that Hafsun died as a Catholic, and that Abd-el-Rahman III had his body disinterred and desecrated as an example to the population). Thus by 1492, when Granada was finally re-conquered by Catholics, no Catholics could be found in the city. The process of Catholic cultural and religious extinction in al-Andalus was similar to what one can witness in the Middle East and North Africa today, where the Christian population has been steadily declining from a time when most of the Middle East and North Africa was Christian, prior to the Islamic conquests.
For a more detailed treatment of these issues see my "The Myth of the Andalusian Paradise" at http://www.isi.org/journals/archive/issue.aspx?id=f6e1ad61-8699-4622-9d66-3d4aac01b072
Professor Dario Fernandez-Morera