In January 1439 the streets of Florence teemed with onlookers. A procession from the East had arrived for a Council of the Church. Historian Diarmaid MacCulloch writes in A History of Christianity that “such a widespread representation of contemporary Christianity had not been seen since the Council of Chalcedon,” a thousand years before. Two spectacles in particular captured the imagination of the Latin Christians. First, there was Ethiopia’s Church, the very existence of which had been but a rumor in Medieval Europe, cut off from Western Christendom for centuries, represented at the council by two emaciated monks. Then there was the delegation from the Byzantine lands, whose emperor, John VIII Palaiologos, was the heir of Constantine and Justinian.

As the successor to Constantine, John—who rode at the head of the Greek-speaking delegation toward the cathedral of Santa Maria del Fiore—still bore the title “Caesar.” And like Constantine at Nicaea 11 centuries before, John’s singular focus was on ending theological disagreements that had undermined political unity. John hoped to save his dying empire from the aggressive, expanding Ottoman Turks.

The pomp and ceremony of this “despot” from the Orient, however humbled by desperate circumstances, captured the imagination of Early Renaissance Florence, and the impression left by him and his retinue influenced art, fashion, and philosophy for generations. George Gemistus Plethon, the century’s most distinguished Byzantine philosopher, lectured on pagan philosophy while in Florence, inspiring Cosimo de’ Medici to found the Platonic Academy, which informed Renaissance humanism through the reintroduction of classical Greek thought to the West.

The council, however, became mired in doctrinal disputes, ranging from the arcane (Filioque and Purgatory) to the seemingly mundane (circumcision and unleavened bread). Upon reaching an impasse, the Emperor John, once more in the manner of Constantine the Great, exerted pressure on his prelates to reunite with Rome. But John did not succeed. Internecine squabbles and external political influences destroyed what fragile unity briefly appeared in Florence. In the end, both the religious and political objectives of the council failed. Few such attempts at Christian unity would follow in the centuries thereafter, and none so ambitious.

In 1453, John’s successor, Constantine XI, died fighting the Turks on Constantinople’s ancient land walls, and the city fell. Many Byzantine refugees fled to Italy, where they resumed the cultural encounter begun in Florence, leading to a European rebirth rooted in Hellenic philosophy and art. The Greek refugees were gradually absorbed into the culture of Latin Christendom. Those Christians who remained behind in Southeastern Europe, Anatolia, Egypt, Mesopotamia, and the Levant endured, now without an emperor, and saw their fortunes wax and wane, increasingly a minority in the lands of their—and Christianity’s—origins.

Latin Western Europe, revitalized by its encounter with classical antiquity through Byzantium, looked now beyond the frontiers of the ocean, discovering and conquering new worlds. In America, Christianity, transplanted from Europe and strongly influenced by the Protestant Reformation, underwent successive waves of revivals and awakenings, becoming further removed from its origins among Europe’s churches and from Christianity’s origins in the Middle East.

The Council of Florence, though more than five centuries removed from us today, provides striking insights into the increasingly perilous status of Middle East Christians today. The rise of Islamist extremism in the Middle East in recent decades has driven many Christians there from their ancestral homelands. The persecution of Christians in Egypt, Iraq, and Syria—ranging from discrimination to genocide—has displaced, temporarily or permanently, millions of Christians. Those Middle East Christians who resettle in America are for the first time encountering American Christianity in its home.

Middle East Christians have, of course, encountered American missionaries; indeed, the efforts of Protestant missionaries to convert Orthodox and other Eastern Christians to Evangelical Christianity have long been a source of tension. But from the charisms of Pentecostalism to the eschatology of Dispensationalism, American Christianity in its homeland appears very foreign to those whose religious customs and culture have changed little in 2,000 years. Even Catholicism in America liturgically and culturally resembles less the Melkite or Maronite rites than it does those of Anglicanism, Presbyterianism, or Lutheranism.

Thus do two very different Christian communities encounter one another today. It is an encounter in its early stages, but its outcome may be as consequential for Middle East Christianity as the Council of Florence was for the fate of Byzantium.

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In 2014, the church bells of Mosul fell silent for the first time in 16 centuries following the onslaught of ISIS—a new and terrible evil that has engulfed Mesopotamia, driving out Christians by the tens of thousands, slaughtering countless Yazidis, Muslims, and others in its path. Against this background, several patriarchs of the ancient Christian churches came to Washington in September of that year to plead with Western religious and political leaders to save their besieged communities, including the Archbishop of Washington, Cardinal Donald Wuerl, who was instrumental in bringing the summit about.

The patriarchs’ entry to Washington was highly publicized, and carried with it a hint of the spectacle (and politics) that accompanied the Byzantines to Florence. Unlike those in Florence, however, these ancient Christians from the East had no Caesar and no state. On September 9, they gathered in an ecumenical prayer service with their American friends as a symbol of unity. This quasi-liturgical event seemed to contain within itself much of the paradox and tension that it sought to diffuse, as protocol complicated presenting Evangelical leaders along with the patriarchs. Still more problematic, the urgent nature of the event had left insufficient time for many Evangelical leaders to participate at all. The following day, the patriarchs and other diaspora Christian leaders gathered at the U.S. Capitol, where the crowd of several hundred heard from more than 20 congressional leaders. On September 11, the anniversary of al-Qaeda’s 2001 attack on America, the patriarchs met with President Obama to plead for help against the radical offshoot of al-Qaeda that had carved out of Syria and Iraq a purported Caliphate.

The objectives of the summit were to foster greater unity between Middle East Christians living in America; to make their voices heard in Washington; to convey to American leaders the urgency of protecting their vulnerable flocks; and to lay the groundwork for greater collaboration with America’s Christians, particularly Evangelicals, in the future. Yet the cultural divides were apparent almost immediately. One cable news producer covering the story, upon seeing photos of the patriarchs from the Middle East in their traditional attire, asked why so many of the summit’s prominent guests were Muslim. It was an innocuous mistake, but one that foreshadowed miscues to follow.

A scuffle between two Middle East Christians on Capitol Hill was broken up by a tiny Assyrian nun. Shortly thereafter, the patriarchs were taken, unwittingly, into a congressional hearing on the war crimes of Bashar al-Assad by congressional staff who, also unwittingly, did not realize that the Eastern Christians’ lives could be endangered by their attendance at such a hearing. They were hastily ushered out. There were other unpleasant incidents, some highly publicized, some not.

Among those that did gain public attention was an incident in which Sen. Ted Cruz announced that the Christians of the Middle East had no greater ally than Israel, which drew a generally negative response from the audience—particularly from those who had to return to Lebanon, Syria, and Iraq, where their lives and the lives of their families would now be threatened. Some believe that Senator Cruz deliberately baited the audience to capitalize politically in the lead-up to the 2016 race; others think that he stepped naively but without malice into the complexities of the Middle East, framing the issue in polarized terms that might make for good politics in the Bible Belt but that are incompatible with Middle East reality. Whatever the case, it is safe to assume that Cruz did not foresee anything like the backlash that came from Christian, particularly Catholic, and conservative journalists, many of whom were in the room. In the days and weeks that followed, uncomfortable conversations long overdue took place inside the Beltway. What to do about—and for—the Christians of the Middle East?

Initially caustic reaction to these strange Christians from the East has given way to thoughtfulness, especially on the part of many Evangelicals. This spirit was captured by the Evangelical author Eric Metaxas, who said before his September 11 keynote address at the summit, “I really just want to understand.”

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Byzantinologist Steven Runciman, writing about the essential distinction between Greek and Latin Christians, observed that the two simply “felt differently about religion; it is difficult to have a debate about feelings.” The same might be said of the encounter between American and Middle East Christians today. It is not, after all, merely theology that accounts for the cultural gap. There are fundamentally different attitudes and experiences regarding the role of institutional Christianity vis-à-vis the state, the news media, and civil society, and different perspectives on war and peace—all of which have evolved quite separately in the East and West for the better part of two millennia.

Despite a sincere desire to help, American Christians are often separated from those of the Middle East not only by language but by politics, ethnicity, heritage, and perhaps most significantly, culture. There is an inclination to regard “the other” as precisely that. Middle East Christians are often mistaken by Americans for Muslims because of their Middle Eastern appearance, names, and use of Arabic, bringing to mind the Medieval Latin Christian tendency to refer to the Greeks of Byzantium as “pale-faced Turks.” Mark Movsesian noted that “Mideast Christians have the misfortune to be too foreign for the Right and too Christian for the Left.” Middle East Christians, for their part, are often befuddled by Evangelical theology, much of it shaped by an eschatology with immediate geopolitical implications.

There are certain fundamentally different attitudes toward war and peace. Whereas American Christians, Catholic or Protestant, have comparatively little hesitation about military service or killing in combat, Middle East Christians have views more in the tradition of the Eastern Church Fathers, many of whom believed that war was essentially sanctioned murder. Saint Basil, in an extreme interpretation of this view, held that Christian soldiers who kill in battle may not receive the Eucharist for three years. By contrast, medieval Western Christians—influenced by Augustine’s just war theory, the chivalric tradition, and the Norse-Germanic comfort with mortal combat—were far more prone to engage in military action than their Byzantine counterparts, who remained deeply influenced by early Christian pacifism and a preference for diplomacy. That preference still dominates Eastern Christianity.

Where church practices are concerned, Middle East Christians have liturgies of the kind the Reformers in the West dismissed as formalisms that detracted from a personal encounter with Christ. Whether Orthodox, Coptic, or Catholic, they typically submit to a rigid ecclesial hierarchy, with patriarchs still based in the Middle East. Evangelicals, on the other hand, tend to practice a faith more individualistic, autonomous, and non-hierarchical. It is these very qualities that allow Evangelicals to mobilize movements rapidly—precisely the kind of movements Middle East Christians now desperately need. (Sweeping generalizations can be counterproductive, of course, failing to grasp the vast diversity and complexity of Christians and Christian thought. They fail, for example, to underscore a small but steadily rising demographic: Arab Evangelicals.)

Middle East Christians have much to learn from American Christians about engagement in their country’s public life. Whereas American Christians have highly developed notions of liberty and little patience for being exiled to the margins of the public square, Eastern Christianity never had its Canossa—that moment of emerging from the state as a rival, independent institutional power. In consequence, an essentially Caesaropapist tradition continues in variations across the Middle East to this day, sometimes leading to lurid political bedfellows. Deference to those in power is alien to Anglo-Protestant political culture, which is far more likely to push back against the encroachments of the state—a luxury, Middle East Christians will argue, that they do not possess. Russell Moore of the Southern Baptist Convention proudly noted at Georgetown University earlier last year that Baptists “have a history of being irritants.” As Middle East Christians in America attempt to organize into a more cohesive advocacy group, they may learn from American Protestants that they will get further as irritants than as supplicants.

For Greek and Latin Christians in the 15th century, cultural attitudes proved more difficult to reconcile than theological differences. To succeed where their spiritual forefathers failed, Middle East Christians living in America today must work to overcome cultural barriers by reaching out to Evangelicals in their own communities, from whom they can learn to be successful advocates for their brother and sister Christians who wish to continue living in the Middle East. Evangelicals, in turn, must come to understand the complexity and richness of Middle East Christianity, whose faith and practices have been handed down largely undiluted over two millennia from the earliest origins of the Christian faith—a vital cultural source for American Christians, akin to the classical learning that the Byzantines brought to the West at Florence.

The cultural gap that exists between Middle East and American Christians today may be wider than the one between Greek and Latin Christians in the 15th century. The means are available to close this gap rapidly, however, through communication, personal encounters, and above all good will. Many individuals and organizations are endeavoring now to bring this about, and there is much work underway to promote grassroots political organization, direct humanitarian assistance, political advocacy, and programs for long-term sustainability. But the most fundamental work consists first in seeking to understand the other.

Andrew Doran is a senior advisor for In Defense of Christians.