The recent migration is an acceleration of an established trend of Iraqi Christians seeking opportunities elsewhere. The withering cycle of warfare and sanctions has prompted as much as half of the nation's Christian population to emigrate since the 1980s, community leaders say.
The great majority of Iraqi Christians are Chaldeans, an Eastern Rite Catholic group. Other groups -- Assyrians, Syriacs and Armenians -- also have lived here for generations. One sect, the Mandaeans, are followers of John the Baptist. Some Christians still speak and hold services in a modern-day form of Aramaic, the language Jesus is said to have spoken.
A smattering of Protestants and Roman Catholics also have lived in Iraq since the period of British rule after World War I. In addition, the fall of Hussein has drawn Protestant missionaries.
Coordinated bombings of at least seven Baghdad churches in the last four weeks followed attacks on churches in Baghdad and Mosul in August that left 11 dead and 50 wounded. Some churches have suspended Sunday services.
Numerous Christian-run liquor stores have been firebombed and forced to close. Because alcohol is taboo to Muslims, Christians traditionally have been the only Iraqis licensed to sell it.
"We've always been able to do our job and live with our Muslim neighbors in peace, but now all that is changed," said Imad Polis Jajo, whose liquor store in Baghdad was firebombed last summer.
A few days after the bombing, a letter arrived at Jajo's door. If he attempted to restart the business, it warned, his 15-year-old son, Rafeef, would be kidnapped. Jajo is now unemployed and must seek help from relatives, he said during a recent interview at a near-deserted Christian social club in central Baghdad. Its gloomy emptiness attested to the fear that has gripped the Christian community here.
"Even during the time of Saddam we were free to come to our club," said Sameer Khouri, the administrative secretary of the facility. "Now, people are afraid to leave their homes."
In Mosul, some Christian women have acceded to anonymous demands to modify their dress in accordance with Islamic code as a means of self-protection.
"I put on the hijab [head scarf] ... to prevent being harmed by these crazy people," said Dalia Ishaq, 18, a student at the Fine Arts Institute for Girls in Mosul. She blamed the excesses on extremists.
"All my friends are Muslim girls," Ishaq said, "and this threat would never change my relationship with them."
Throughout Iraq, Christians interviewed echoed those sentiments, emphasizing their ties to Muslim neighbors.
"I have so many Muslim friends, and they have never treated me harshly -- they are just like my sisters," said Rana Saeed Jerjees, 25, a teacher in Mosul. "I think there are certain people who want a civil war to break out in Mosul and all over Iraq. This is all part of a major plan, and we must never surrender to such schemes."
Mainstream Muslim clerics and the Iraqi interim government have repeatedly condemned sectarian attacks on Christians. The nation's interim constitution explicitly recognizes religious freedom and the rights of minorities.
However, many Christians wonder whether the government -- battered by an insurgency and needing U.S.-led multinational troops to maintain some semblance of order -- can prevent such violence.
One plan under consideration is for Christians to field a slate of candidates for January's elections to ensure that they are represented in the 275-member National Assembly.
Another idea that has met with a cool reception among Christians is the creation of a kind of Christian safe haven in the plains of Nineveh province, outside Mosul. Proponents hope to attract Christians who have left the country, but others fear a kind of rural ghettoization.
"We don't want to be refugees in our own homeland," said Yunadam Khanna, a Christian representative in Iraq's interim parliament. "There is a general crisis in Iraq, and what is happening to the Christians is part of that crisis."
Times staff writer Suhail Ahmed and special correspondent Said Rifai in Baghdad, special correspondent Roaa Ahmed in Mosul and staff writer Tony Perry in San Diego contributed to this report.