I used to think along similar lines as the I regarding Islam. It is true that the Muslim armies did do damage against the Christian Church in Ethiopia, and I used to dislike Islam for demoting Jes-us from God to merely a Prophet. But I have changed I views since then after Learning from Selassie I's Teachings. I have learned that it is better to focus on Correcting Iself than criticizing other religions.
Ahmad Gragn did serious damage to the Ethiopian Orthodox Church and the Muslim armies' conquest of the Middle East kept Ethiopia isolated from the rest of Christendom.
The period following the rise and the rapid expansion of Islam in the near and the Middle East was a very critical one for the Christian kingdom of Axum. The whole civilization and culture of Axum, as well as its economic life, was based on its international maritime connections, Ever since the Egyptian Pharaoh Ptolemeys had taken a scientific and economic interest in the Red Sea area, Axum had become an integral part of the Hellenic world. Axum held the same position also during the Roman and Byzantine Empires. It was indeed not a mere coincidence that the Church in Axum was established immediately after the Emperor Constantine made Christianity the state religion of his Byzantine dominions. There seems to be no doubt, now, that there were many individual Ethiopian and foreign Christian's residing in the Aksumite kingdom, even before the formal establishment of the Church there. But the crucial step taken by Ezana to adopt the new religion and to make it a state Church followed upon a similar imperial decision by Constantine. It was also from the Eastern Mediterranean that the first Christian missionaries come to Axum. Abune Salama and others such as the Nine Saints came from the Byzantine world, and endowed the Aksumite Church with its earliest characteristics. These regular contacts continued down to the seventh century, and all-important economic, political, and religious developments in the Byzantine world were also reflected in Axum. With the rapid Muslim conquest, however, these historical channels of communication were almost completely cut off. Only with the Alexandrian Church did Christian Ethiopia continue to have precarious contact.
Before the rise of Islam, Axum was an extensive maritime and commercial Empire. In its heyday, it ruled many districts in the southwestern part of the Arabian Peninsula, across the Red Sea. It controlled the land of the Beja, a people who inhabited northern Eritrea and what northeastern part of the Republic of the Sudan. In the west, the political and military sphere of influence of Axum had already reached the Nile valley by the fourth century A.D. Beyond the River Takazz'e, the district of Semien and probably also the region as far as Lake Tana were within its territorial limits. However, it was in the south, in the predominantly Agew populated areas of Tigrai, Wa'ag, Lasta, Anogot and Amhara where the heritage of Axum struck its deepest roots. When almost completely excluded from the Red Sea trade, and having lost its maritime international orientation, the kingdom of Axum turned towards this Agew interior, and made it the center of a distinctive Christian culture over the centuries.
The rulers of Axum had acquired strong footholds in these central highlands already before the establishment of the Christian Church in the kingdom. They sent numerous expeditions of war and conquest into these areas from where they obtained tribute and a continuous supply of ivory, gold, and slaves. The Aksumite governor of the Agew was responsible for the long-distance caravan route to Sassou-some where near Fazolgi in eastern Sudan -from where Axum obtained much gold. These precious commodities were used for the international trade across the Red Sea in which Aksum was most active.
After their conversion to Christianity the kings of Aksum consolidated their power by establishing churches and military colonies in these central highlands. There are still today a number of churches many of them dug out of the living rock in Tigrai and Lasta-which are attributed to the early Christian kings of Aksum. These churches and military settlements became centers of still further movements of small family groups from the more crowded parts of northern Ethiopia. In this way, the areas as far south as the region of northern Shoa were gradually affected by these slow population movements. Local traditions indicate that already in the tenth and eleventh centuries a number of small isolated Christian families had been established in the districts of Menz, Merhabite, Muger, and Bulga in northern Shoa. The spear head of Aksumite expansion may have even further south and east. This seems to be suggested by the geographical distribution of some of the Semitic languages of Ethiopia-Amharic, Argobba, Harari, Guragi, and Gafat.
With the Ottoman (present day Turkey) conquest of the Greek Byzantine Capital of Constantinople, the whole Near and Middle East, Islam was given a special impetus in the Red Sea area and in the African Horn. The Muslim communities of the Ethiopian region began to be more and more aggressive particularly in their relations with the Orthodox Christian Empire. Many Turkish and Arab mercenaries came over from across the Red Sea, better equipped with the superior arms of the Ottoman Empire. The Muslim invasion of the Ethiopian highlands in the beginning of the sixteenth century was thus a tremendous success. The leader of the Muslim forces during this conflict was Imam Ahmad Ibn Ibrahim or Gragn, as he is known in Ethiopian Chronicles. His Chronicle, entitled Futuh al-Habasha (meaning “The Conquest of the Abyssinians”), relates how the Muslim invasion was particularly aimed at destroying the Orthodox Church in the Ethiopian highlands. As the center of the mediaeval Christian culture of Ethiopia and as the place where the kings also kept their fabulous treasures, the Church was attacked by the Muslim forces with particular fury. Dazzled by the riches of the Churches and Monasteries, the Muslim troops burnt and looted for a period of about fifteen years, and almost completely destroyed the mediaeval heritage of Orthodox Christian Ethiopia. The following passage is a vivid description of how the island monastery of Hayq was sacked, and it characterizes the attitude of the Muslim army throughout the period of their success between 1531 and 1543:
“They carried off the gold… there were crucifixes of gold in great quantity, books with cases and bindings of gold, and countless statues of gold; each Muslim took 300 ounces; each man had sufficient gold plate to satisfy three men. They also took a vast quantity of cloth and silk… The next morning (the Muslim chief) sent the Imam three rafts loaded with gold, silver and silk; there were only five men on board, two in front and three at the back, the rest of the raft being covered with riches though it could have carried 150 persons. The cargo was unloaded in front of the Imam who marveled at it and forgot the treasure which he had seen before. The rafts returned to the island and were a second time loaded with riches. They came three times, on each occasion loaded; they then returned to the island and the men went on board to return to the mainland. On the following day Ahmad partitioned the spoil; he gave one part to the Arabs and … one to the troops who had gone on the water; the rest he divided among the Muslims”.
It was in this way that the material and spiritual heritage of Mediaeval Orthodox Ethiopia, like that of the Greek Byzantine Church, was destroyed during the wars with Islamic hordes. Many of the inhabitants in the Muslim-occupied areas were forced to renounce their Orthodox Christian faith and adopt Islam. Although some chose to die for their faith, the large majority of the Christian peasants acquiesced to at least a nominal acceptance of Islam.
Here are some links to some previous Reasonings:
Ethiopian Church History
JUZ 6 Surah 4 verses 153-159