|monastery of Dair Abu Maqar (source)|
Under the Caliphs the literary and scholarly skills of Christian monks were highly prized, with many monks serving as clerks and even
high ministers. The most famous is perhaps the great defender of icons John of Damascus (655-750), who was originally a prominent minister for the Umayyads at Damascus before taking orders and retiring to Mar Saba near Bethlehem, where his cell is still exhibited to visitors. Christians such as Hunayn ibn Ishaq (Johannitius) were the leaders of the famous translation academy Bayt al-Hikma (House of Wisdom) at Baghdad in the ninth century
Somewhat paradoxically, Coptic monasticism in Egypt flourished under Islam and may have reached its height in the tenth century. This was because under earlier Byzantine rule, Coptic monasticism was suppressed as heretical, whereas it was tolerated by the Muslims. Although there were certainly attacks against monks and monasteries by Arabs, these tended to be incidents of brigandage or extortion by corrupt officials rather than formal government policy. Throughout the Middle Ages, relations between the Egyptian government and the Coptic monks generally remained good. For example, the late thirteenth century Egyptian Mamluk sultan Bbaybars 1 (noted for his pursuit of Jihad or holy war against the crusaders) was a guest of the monks at a monastery of Dair Abu Maqar (Saint Macarius) while traveling in Wadi Habib.
Thus, despite minority status and intermittent persecutions, Orthodox, Syriac, Coptic and Nestorian monasticism all survived in Islamic lands up to the period of the crusades. Based on the Qur'an, the traditional islamic interpretation was that monasticism was a well intentioned human institution whose advocates did not always live up to its principles. It was not, however, revealed by God. This was the prevailing Arab attitude towards monasticism at the beginning of the crusades
This blog draws freely on the paper "Muslim perspectives on the military orders during the crusades" by William J. Hamblin, published in BYU Studies.