As I noted in an earlier post, Christian decline in the Middle East covered a period of many centuries. As early as the 9th century, we find Christians converting to Islam for any number of reasons. The almost total destruction of the Christian infrastructure during the Mongol invasions (13th century) further weakened the Christian position.
Under the Ottoman Empire (from the end of 13th century until 1923) the status of Christians further deteriorated. The Ottoman Empire did everything possible to expand its borders. For several centuries, it enjoyed considerable success. Most of the Balkan countries, parts of Hungary and Poland and all of Greece came under Ottoman rule. All of these countries were Christian — Orthodox, Catholic or Protestant. The Ottomans employed the millet (originally Arabic for: religion, religious community, nation) system in which each religious group enjoyed a certain autonomy and lived under its own denominational leadership and laws. But each remained under the strict control of the Ottoman overlords. While this provided a certain autonomy, it also ran the risk of “ghettoizing” and, hence, isolating the communities. At the same time the same social, cultural and financial incentives continued which would entice Christians to convert to Islam.
In the 19th century the Ottoman Empire entered a period of decline. There were large groups like Greeks, Armenians, Assyrians and others who became restive. Nationalist movements began to emerge and many of these groups sought independence. In 1821 Greek nationalists revolted against the Ottoman Sultan Mahmud II. The patriarch of Constantinople, Gregory V, who was also the leader of the Greek millet, opposed the revolt. Nevertheless, the Sultan held him responsible. On 22 April 1821, Easter Sunday, the Ottomans arrested Gregory after the liturgy and hanged him in full vestments on the gate of the patriarchate, where his body remained for two days. This not only enflamed the Greeks but also encouraged Russian, French and British intervention on the side of the Greek rebels. Ultimately the rebels were victorious and Greece achieved independence in the Treaty of Constantinople in May 1832.
The success of the Greeks was a shock to the Ottomans. They had been invincible for centuries. Soon other Christian millets became possible hotbeds for revolutionaries. The intervention of Russia, France and Britain on the side of the Christian Greeks was a warning to the Ottomans.
At the outbreak of World War I (1914-1918), the Ottomans joined on the side of Germany and Austria-Hungary against the British, French and Russians, who not coincidentally had supported the Greek war for independence. After some initial successes, it became clear that the Ottomans were on the losing side. Christian millets were looked upon as possible areas for revolt and for support of the Allied Powers. In fact, some of the millets, like the Armenians, did see an opportunity for independence.
In 1915 the Ottomans began a systematic extermination of Armenians, the vast majority of whom were Christians. It should also be noted that Armenians were widespread in the Ottoman Empire. In what the United Nations and others, including Pope Francis, refer to as the Armenian Genocide, over 1.5 million Armenians were either executed or died from starvation and forced migration. While the Armenians have received the attention of Western historians, they weren’t the only ones who faced persecution and death. Other groups, including the Assyrians and Chaldeans, were also massacred.
The end of World War I and the dissolution of the Ottoman Empire allowed the French and British to divide up the Ottoman remains along lines of their own national interests. The Sykes-Picot Agreement (1916) created artificial countries in the area of Syria Mesopotamia. Created according to British and French national interests — and not linguistic, ethnic, religious or political considerations — these countries were and are inherently unstable. As British and French control in the region began to wane, many of these countries experienced anti-colonialist revolutions and sought their identities in a non-European, non-Christian (which to many in the region was the same) Islam. Once again, especially in Iraq, Christians became the target for massacres. Beginning in 1933 there were several massacres of Assyrian Christians, the worst event being at the town of Simele on 10-11 August of 1933.
By this time Christianity in the region was in sharp decline. The Christian population of Turkey in 1914 was estimated at 14 percent. By 2017 it had sunk to 0.2 percent. Genocide, emigration and expulsion reduced the Christian population, which had been the majority in the 6th century, to an insignificant minority in the 21st.
The wars the United States waged against Iraq (2003 to the present) further worsened the situation of Christians, who were often caught in the crossfire of competing forces or targeted as traitors, sympathetic to the (Christian) invaders. Having once numbered more than 1.5 million, Christians now number 150,000 or less in Iraq. The Syrian Civil War (2011-present) and the rise of the Islamic State have made the situation of Christians in Syria and Mesopotamia almost intolerable.
Whether Christianity will or even can survive in the region is today a very open question.
Related:
2,000 Years of Christianity in Syria and Mesopotamia: Introduction
2,000 Years of Christianity in Syria and Mesopotamia — Part 1: In the Beginning
2,000 Years of Christianity in Syria and Mesopotamia — Part 2: Christians and Muslims Co-exist
2,000 Years of Christianity in Syria and Mesopotamia —Part 3: Christianity Begins to Decline