The pews at First Baptist Church of Bethlehem fill quickly as congregants stream in on a Sunday night, some with fancy purses, others with worn shoes and KFC takeout bags. Latecomers have to settle for plastic chairs in the back.

As the service gets under way, hands arc in the air as worshipers sing and thank God for a recent revival that drew more than 1,300 people to hear the message of the Bible - a testament to the theme of the sermon on this night: responding to the invitation of Christ.

In a city heralded as the place where Jesus Christ was born to the Virgin Mary, the church is something of a modern miracle. Founded in a two-bedroom apartment three decades ago by the Rev. Naim Khoury, First Baptist was bombed 14 times during the first intifada, struggled with financial difficulties, and is now facing a legal battle with the Palestinian Authority, which doesn't recognize it as a church.

Thousands of Christians in Bethlehem have faced similar political and economic strife over the past few decades, leading many of them to flee the city where Christianity's central figure was born in a straw-filled manger. Christians, who once made up 80 percent of the population, now represent 20 to 25 percent. But First Baptist defies the trend. Its congregation is 300 members strong - and growing.

"We fought and fought to remain and not to hide what we believe," says Mr. Khoury, who himself survived a bullet to the shoulder from an unknown sniper while in the church parking lot five years ago. "It's time for them to realize that we are here. There's no way for us to close down and go somewhere else.... We proved ourselves here by the help of the Lord that we are here to stay until the Lord comes back."

Khoury's unflinching faith is something that more Christians may have to summon - not only here in the Holy Land but across the entire Middle East. Two thousand years after the birth of Jesus, Christianity is under assault more than at any time in the past century, prompting some to speculate that one of the world's three great religions could vanish entirely from the region within a generation or two.

From Iraq, which has lost at least half of its Christians over the past decade, to Egypt, which saw the worst spate of anti-Christian violence in 700 years this summer, to Syria, where jihadists are killing Christians and burying them in mass graves, the followers of Jesus face violence and vitriol as well as declining churches and ecumenical divides. Christians now make up only 5 percent of the population of the Middle East, down from 20 percent a century ago. Many Arab Christians are upset that the West hasn't done more to help.

Though many Muslims grew up with Christian friends and colleagues, powerful political and social forces have made such coexistence more difficult. As political Islam gains support, Christians can no longer find refuge in a shared Arab identity with their Muslim neighbors, but are instead increasingly marooned by an emphasis on religious identity. Calls for citizenship with equal rights are punctuated with stories of Islamist extremists demanding that Christians convert to Islam or pay an exorbitant tax. And many Muslims are facing persecution themselves as the Arab upheavals of 2011 continue to ripple across the region and nations try to find an equilibrium between freedom and stability.

"Whatever happens, it is going to be very difficult to put it back together again," says Fiona McCallum, a scholar of Middle Eastern Christians at the University of St Andrews in Scotland.

To be sure, Christians have confronted difficult times before, from the killing of Jesus' immediate followers to the Mamluk oppression of Christians beginning in the 13th century to the rise of Islamist militant activity in Egypt in the 1970s. Warriors who came in the name of Christ have been responsible for egregious interreligious violence as well, such as during the First Crusade in 1099, when Christians took over Jerusalem and massacred nearly all the city's residents.

Whether today proves to be yet another ebb in the flow of Christian history or something more fundamental remains uncertain. But what is evident is that both Muslims and Christians, as well as the region's other minorities, are likely to be significantly affected by a continued deterioration.

Christians have traditionally run some of the region's top schools, been active members of the merchant class, and brought a moderating influence to society and politics. That has led not only Christians and human rights activists to lobby for the preservation of these communities, but some Muslim leaders as well.

"The protection of the rights of Christians is a duty rather than a favor," declared Jordan's King Abdullah in September, speaking to delegates at a palace-sponsored conference on Arab Christian persecution. "Christians have always played a key role in building our societies and defending our nations."