By Wall Street Journal
Surrounded by a blast wall topped with razor-sharp concertina wire, Our 
Lady of Salvation Church in downtown Baghdad resembles a fortress more 
than a sanctuary. Despite the fortifications, however, those who worship
 there are feeling more vulnerable than ever. 
An appeal for 
help in guarding the Syriac Catholic Church this month brought no 
volunteers. A ragtag trio of armed men protects the churchyard. At Mass,
 guards patted down worshipers and checked their belongings for 
concealed weapons and explosives. Only a few dozen people occupied the 
pews, the wan echo of their voices lost in the vast nave where hundreds 
used to worship each week.
As Sunni militants of the Islamic State
 of Iraq and al-Sham, or ISIS, sweep through the country, the church's 
small congregation and makeshift defenders highlight the precarious 
condition of Iraq's Christian community. The community's ranks have 
shrunk by half in the past decade, as the devout flee the sectarian 
violence that has become a hallmark of post-Saddam Hussein Iraq.
One
 man at the church said that the country's largest religious 
communities--Sunni Muslims and Shiites--have often been too busy 
fighting each other to hunt Christians, but it is different this time.
"Now
 all these terrorists are here from across the Middle East, and they 
want to cleanse the Christians," said a 35-year-old armed guard at a 
checkpoint outside the church's main entrance. "The youth have left. 
There's no one left to defend the church, and if I had the chance, I'd 
leave, too."
In 2010, the congregation had a taste of the perils 
that possibly lay ahead. At least 58 people were killed when ISIS 
militants attacked the church and took more than 100 hostages.
While
 the members of Our Lady of Salvation worry that they will again be 
targeted in a sectarian attack, other Iraqi Christians are simply trying
 to avoid being caught in the tightening vise of extremist Sunni 
fighters and their foes.
On Tuesday, Syriac Catholics were among those fleeing the northern town
 of Qaraqosh as clashes raged between ISIS and Kurdish Peshmerga forces,
 residents said. ISIS mortars intended for the Peshmerga hit Qaraqosh, 
triggering the exodus of most of the 50,000 residents to Iraq's 
autonomous Kurdistan region and its capital, Erbil.
A small 
fighting force stayed behind in Qaraqosh to defend its religious sites, 
some dating to the eighth century. The Iraqi military was stretched too 
thin to help, said Ammar To'ma, a member of parliament's security and 
defense committee.
"No one is left in the village," said a teacher from Qaraqosh, who escaped to Erbil on Wednesday. "It was total chaos."
Increasingly,
 Christians risk becoming collateral damage in the main sectarian 
battle, said Bassim Bello, the mayor of nearby Tilkif.
"The 
Christians are the weakest chain in Iraq's society, and we've always 
warned that we will be the victims of any fighting," Mr. Bello said.
In
 Baghdad on Tuesday, Yonadam Kanna, a member of parliament and the 
leader of the main Christian party, the Assyrian Democratic 
Movement,paced nervously in his office as he watched the news from 
Qaraqosh.
In search of help, he called the United Nations mission 
to Iraq, the U.S. Embassy and the Iraqi military. He reached no one of 
influence, so he left messages.
"We're trying to stop those bloody
 guys," Mr. Kanna said, referring to ISIS. "I'm not confident we can. 
They are aggressive and have heavy weapons. We only have a few 
Kalashnikovs."
While he waited impatiently for his calls to be 
returned, Mr. Kanna recalled the days when Iraq's Sunnis, Shiites and 
Christians celebrated religious holidays together and intermarried, and 
Baghdad boasted a vibrant Jewish community.
In today's Iraq, 
Shiites make up about 60% of the population and Sunnis 32%, while 
Christians and other minorities compose 3%, according to the CIA World 
Factbook.
For Mr. Kanna, the intolerance of ISIS militants toward 
non-Sunni religious faiths isn't entirely to blame for the dwindling 
Christian community. Christians themselves, he said, have chosen to 
emigrate rather than struggle to keep their foothold in Iraq. He accuses
 Western nations, even the U.S. president, of encouraging their flight.
"I
 told Obama to stop the immigration of Christians. Stop this policy of 
vacuuming up the Christians of the Middle East. It is destroying the 
community," said Mr. Kanna, citing a letter he wrote to the White House 
several months ago.
His homily was interrupted by the ringing of his phone. It was a U.S. Embassy official returning his call.
"Hello. I just wanted to inform you that the biggest Christian community, Qaraqosh, is being attacked," Mr. Kanna said politely.
The embassy official asked Mr. Kanna to identify himself. He sighed.
"You met me yesterday."
Laith al-Haydair contributed to this article.