"This is a safe space," says Mariam, a 17-year-old Chaldean Catholic among the few dozen attending the service.

Elderly women pray solemnly, their hair covered in delicate black veils.

Red ropes block off every other row to enforce social distancing in the midst of the coronavirus pandemic, but there aren't enough worshippers to fill the church in any case.

A few hundred thousand Christians are left in Iraq, where a US-led invasion in 2003 paved the way for bloody sectarian warfare that devastated the country's historic and diverse Christian communities.

Like Mariam, the 53-year-old deacon of St. Joseph's Cathedral preferred to identify himself only by his first name, Nael.

"My father, mother and siblings emigrated after 2003. I'm the only one left in Iraq, and I stayed because I was hoping the situation would get better," he said.

But after 35 years serving at St. Joseph's and watching the parish shrink year by year, Nael has little hope.

"It used to be full even on regular weekdays," he recalled.

"But there's been a drop in numbers and ongoing emigration in the last three or four years, especially from this parish," he lamented.

- Blast walls, rusted locks -

As hardliners fought each other starting in 2006, Iraq's ancient Christian communities -- Assyrian, Armenian, Chaldean, Protestant and more -- were directly targeted.

One of the most horrific attacks was in 2010, when gunmen took hostage and eventually killed dozens of Christians at the Our Lady of Salvation Church in Baghdad.

Then in 2014, the Islamic State group swept across Nineveh province, the heartland of Iraq's minorities.

Christians -- but also the esoteric Yazidis, Shiite Turkmen and other communities -- streamed out of their homes as the jihadists closed in, or were forced to convert under their rule.

There are no reliable statistics on the number of Christians who fled Iraq during these consecutive waves of bloodshed.

According to William Warda, co-founder of the Hammurabi Human Rights Organisation, Christians left in Iraq number up to 400,000, down from 1.5 million in 2003.

Their absence is stark.

Churches across Baghdad have shuttered, including the Holy Trinity Church in the Baladiyat district, closed to regular services for four years.

At the Armenian Catholic Church of the Sacred Heart of Jesus, a terracotta structure in the Karrada area, a rusted lock has barred entry since 2007.

The churches that have remained open are surrounded by a labyrinth of concrete blast walls and security forces.

The southern Baghdad district of Dora was once home to a thriving community of 150,000 Christians, including doctors, businessmen and cafe owners, Warda said.

Now, "there are only 1,000 left," he told AFP.

- 'I have no home in Iraq' -

Iraq declared IS defeated three years ago, but "threats, kidnappings, extortion and deaths still persist," said Yonadam Kanna, a leading Christian politician.

While Iraq's constitution ostensibly affords the same level of protection to all communities, Chaldean Patriarch Louis Sako said de facto prejudice was locking Christians out of society.

"There's no direct pressure on Christians today, but there's day-to-day discrimination. If you're Christian, there's no place for you in state institutions," the head of the Chaldean Catholic Church said.

"It's caused by corruption and it leads to emigration."

That has eroded the feeling of belonging, some told AFP.

"There's a sense among Christians that the country is becoming more conservative, and that Christians -- or even secular Muslims -- can no longer live in it," Warda said.

Ninos, a beautician looking to emigrate, agreed.

"Sometimes, I can see myself here. But most of the time, I find I have no home in Iraq," the 25-year-old said.

"The situation isn't compatible with my work, the way I think or how I aspire to develop myself."

For others, it is a matter of livelihoods.

Iraq has been hit hard by the twin shocks of an oil price collapse and the novel coronavirus pandemic, leading to the worst fiscal crisis the country has seen in decades.

That has pushed Mariam to consider greener pastures outside her beloved homeland.

"Honestly, everybody wants to stay in their own country," she told AFP.

"I dream of travelling, but I dream at the same time that my country could provide me everything that others have, so I could stay here."