When I was Jordan’s ambassador to the United States 20 years ago, I gave a lecture at a Presbyterian church in Washington, D.C. As soon as I had finished, a man raised his hand. “Mr. Ambassador,” he said, “I understand that you are of the Christian faith. Can you tell us when you converted and what effect this had on your life”? I replied, “With all due respect, sir, I need to ask you that question. I am a descendant of the original Christians. When did you convert?”

Many in the West tend not to know that Christianity originated in what is today the Arab world. It was neither imported during the Crusades nor the result of “conversions.” On the eve of the advent of Islam in the 7th century, most of what is today the Middle East was Christian, including the Levant and North Africa. According to several studies, prior to the Arab conquests the number of inhabitants of the Levant—today’s Syria, Jordan, Palestine, Lebanon, and Iraq, in addition to Israel—was 13 million. The vast majority was Christian, except for some 130,000 Jews and a smaller number of pagans. At that time those inhabiting the Arabian Peninsula, where Islam originated, was only around 1 million, with very few of them leaving with the Arab armies to conquer the Levant and North Africa in Islam’s name.

Arab Muslims did not force the people of the lands they conquered to convert to Islam. They adhered to the Quranic phrase, “There is no coercion in religion,” and obliged minorities only to pay a special tax. Numerical studies conducted on populations in the region show that a hundred years after Islam, only 6 percent of the Levant’s inhabitants was Muslim, with the rest having remained Christian. By the end of the third century after Islam, Christians still constituted 60 percent of the population. At the onset of the First Crusade, five centuries after Islam, Arab Christians and Muslims were about equal in numbers.

This indicates two facts. The first is that Christians represented the overwhelming majority of inhabitants of the region long before Islam did. The second is that most Arab Muslims today were originally Christians. The two communities have the same blood, the same DNA, and the same commitment to their land.

In fact, the European crusaders, when they conquered the Holy Land, viewed Arab Christians as “heretics,” though they were descendants of the first Christians. They killed many of them, in addition to Muslims, particularly when they occupied Jerusalem in 1099. Many Arab Christians, though not all, sided with their compatriots during the Crusades, rather than with their coreligionists.

Today, the situation is vastly different. Arab Christians, who were the first converts to Christianity, are dwindling in number to an alarming degree in most of the Arab world. In Iraq, which has been affected primarily in recent years by forced emigration due to the conflict after 2003 and the later exactions of the Islamic State, the number of Christians has dramatically gone down to an estimated 300,000, less than 1 percent of the population. As recently as the 1950s, they numbered about 10 percent.

In Jordan, Arab Christians number no more than 170,000 people, about 3 percent of the population. In Syria, Christians represented about 10 percent of the population before the recent civil war, but that number has gone down significantly. Only in Lebanon, where Christians make up perhaps 30 percent of the population, and Egypt, where they represent around 8 percent, have Christians maintained a sizable, though decreasing, presence. In North Africa, Christians almost vanished centuries ago.

More importantly, the situation of Arab Christians in the Holy Land is dire. Only about 150,000 remain in the occupied Palestinian territories, including less than 4,000 Christians in Jerusalem. In a generation from now, Christian holy places in Jerusalem, Bethlehem, and elsewhere in the Holy Land risk becoming museum pieces. Equally dangerously, the religious diversity that had long characterized the Middle East, a diversity that engendered cultural richness and allowed different religions and sects to coexist peacefully for centuries, is disappearing. This does not bode well for the different components of Arab societies.

In light of the major transformations in the Arab world today, respect for diversity is central to the development of stable and pluralistic societies. Religious diversity is a key component in building and maintaining that respect. Its absence will be dire not only for Arab Christians, but for Arab culture in general.

The United States has been primarily concerned with the security of Israel in the Middle East. It has failed to consider that the falling numbers of indigenous Arab Christians, brought about in contemporary times by radicalism and the Israeli occupation, will not help the cause of stability or prosperity in this part of the world. The plight of Arab Christians can no longer be neglected.