The Arabic original can be found here. It's worth remembering that this was written in his column in the secular but Orthodox-owned newspaper an-Nahar. While on a scholarly level I wouldn't endorse all of his historical opinions, his understanding of how St. John of Damascus relates to the modern Arab Christian situation is of interest.
Saint John of Damascus
Saint John of Damascus, who was called Mansur ibn Sarjun in the world and took his monastic name in the Monastery of Saint Sabbas which still stands today near Bethlehem, was the grandson of Mansur ibn Sarjun who worked for the Byzantines in Damascus, governing the city. In the Caliphate of Mu’awiya the elder Mansur was appointed to manage the treasury. This was a matter with serious and profound ramifications and the office extended to his son and then to his grandson who bore his name according to this custom in those lands of naming a child after his grandfather.
It is clear that the Umayyads maintained the Christians in the positions they had occupied during the Byzantine period, because the various bureaus kept their records in Greek until they were arabized under Abd al-Malik ibn Marwan. At that time, Greek was still the language of the people in the cities, just as Aramaic was the language of the people in the countryside. In the time of Yazid ibn Mu’awiya, Orthodox Christians had management over the treasury, even though the Jacobites (that is, the Syriac Orthodox) were the majority in Syria. The only explanation I have for this is that the Arabs maintained those whom they found in the bureaus during the Byzantine period and these were necessarily of the religion of the Byzantine rulers.
At the time of the conquest, the Arabs were not able to have administrative positions on account of their ignorance of the language of administration, which was Greek. The political situation was such that the Arab rulers had control over the caliphate and the army. That is, the Arab Muslims were entirely dependent on Christians in their administrative centers to the point that Mu’awiya put the elder Mansur ibn Sarjun in charge of the building of the first Arab fleet at Tripoli, with the goal of occupying Constantinople. In other words, Mansur’s responsibility was to build a fleet in order to attack the capital of the Orthodox world. It was not pleasant for a man who attended the liturgy in the port of Tripoli on Sunday to prepare the Muslim Arab army to attack Constantinople. This was not something easy for him, but he and the sons of his Church understood that the Muslims conquered Syria in order to stay there and that the Christian people of the land had no hope of the Byzantines’ regaining Syria.
To what people did the family of Sarjun belong? I have no evidence that they belonged to an Arab tribe, though there were Arabs among the Christians of Syria prior to the conquest. My opinion is that they were of old Syriac stock and had adopted the Greek language on account of their culture. (Syriac does not mean that they were of the Syriac Orthodox creed, as they were Chalcedonians and both churches used the two main languages).
The fact that Saint John did not write a single line of Arabic does not mean that he was completely ignorant of the language, especially since he and his family mingled with the Umayyad caliphs on account of their administrative work. The reason that John of Damascus did not use Arabic was that this language had not yet become the language of the Christians. But how did Mansur ibn Sarjun the younger, whose name became John of Damascus, address the Caliph Yazid when he would see him every day for consultation about matters of the treasury, when Yazid only knew Arabic? It seems to me that Mansur ibn Sarjun at the very least spoke to the caliph in colloquial Arabic, and everything points to the existence of a colloquial dialect among the Muslims. Saint John of Damascus composed a “Dialogue between a Christian and a Muslim” that has been read by Christian and Muslim men of culture since it was translated from Greek into Arabic and published in Egypt around sixty years ago. This proves to us that John of Damascus knew something about Islam from his friends. Despite that, I do not think that he read Surat al-Ikhlas, which he cites, since he makes a mistake in his translation of a verse. However, there is no doubt that he talked about Islam with Yazid, since he was not particularly pious. That said, Saint John of Damascus did not write anything else about Islam, despite what some scholars have thought.
In the end, the two men parted ways because Yazid attacked some Christian leaders, which caused the saint to leave Damascus for Palestine, where he became a monk. There in the Monastery of Saint Sabbas he composed the Fount of Knowledge which comprises a hundred chapters and is his book about the Orthodox faith. He begins it with a philosophical preface. German orientalists say that it was the foundational source for Islamic philosophy, which began in the Umayyad period. The philosophical problematic in the history of Islamic thought rests on the basis of the Fount of Knowledge.
John’s value in that book is that he is the first writer to put in writing the framework of thought of Christian theology. That is, a writing arranging all Christian thought. Before him, there had only been various compositions on this topic or that, one person writing on the topic of the Trinity, another on the incarnation or redemption, but John summarized all of Christian thought in interrelated chapters.
It becomes clear to one who examines this book that its author knew the early Fathers very well and that he compared them and chose from them as he saw fitting and that he depended in philosophy on Aristotle. Specialists have debated his creative power. No doubt he was less innovative than the greatest of the fathers. Perhaps that is the lot of one who receives a well-established intellectual tradition tied to logic. However, it is his merit that he was the first Christian to cast the faith in one book. He was the initiator of systematic theology. Thomas Aquinas drew on him frequently and in the Summa Theologica he cites him hundreds of times.
It was not enough for Saint John of Damascus to be erudite in theology, because he also practiced asceticism and mystical contemplation and composed numerous church services, including the Paschal hymns that all the Orthodox of the world chant to this day. Besides these texts, he composed the eight tones that till today dominate our chant after there having previously been another system of music. He was thus not simply a man of abstract intellect, but rather his heart was filled with the presence of the Lord.
Naturally, the determination of the family of Mansur in two matters draws our attention. First, that they held fast to their faith completely and with knowledge, and second, that they remained in their faith while honestly serving the government in a state that had become dominated by Arabness at all its levels. I think that the behavior of John of Damascus and his father and grandfather is a model for the stance of Orthodox Christians in an Islamic state, whether or not it accepts them with complete sympathy. They act based on their morals and the state according to its morals.
What is important in this behavior is that the inspiration for these eastern Christians was not based on a nationalism that had not yet been discovered then. Love alone was what motivated them and profound knowledge supported this love. Before the language of the Christians became arabized in Syria, and that took a very long time, the family of Mansur appeared there in complete harmony with the state and they historically received the glory that they deserved.