In June 2014, ISIS stormed Iraq’s second-largest city, Mosul, routing its security forces. Once in command, militants began canvassing neighborhoods. Coming upon houses whose occupants were Christian, they painted the Arabic letter N (ن) on its door, for “Nasrani,” or Nazarene — a term for Christians.

For the Fattah family, this mark inaugurated the greatest hardship of their lives.

“Ten men, 15 to 20 years old, came to our house in Mosul in many cars with guns and swords,” says Rakan Fattah, 45, a tall man with deep-set brown eyes. “They wore fatigues, had long beards and carried the black and white flag of ISIS,” he says.

The unit’s leader, who was maybe 30, entered and gave the family a message: Convert to Islam, pay a tax or be killed.

“They came in and took everything, kicked us out and would not allow us to take anything,” Mr. Fattah says. Conversion was out of the question, and “even if we did pay the tax, we knew we would be killed.”

When it became clear the Iraqi army would not return to liberate the city, the Fattah family fled to Qaraqosh, a Christian town in the Nineveh Plain, carrying only their passports. For three weeks, they lived in an unfurnished building.

Despite efforts by the Kurdish Peshmerga forces to hold ISIS at bay, resistance collapsed and ISIS flooded the plain, forcing tens of thousands of people to flee deep into Iraqi Kurdish territory.

The Fattahs lived on the floor of a church along with 400 other Christians for a month before finally deciding to leave Iraq. They sold their car and bought airline tickets to Amman.

The experience of the Fattah family, though harrowing, is by no means unique. ISIS has uprooted many in Iraq, with current estimates suggesting about four million internally displaced persons and nearly 400,000 refugees abroad — Christians, Muslims, Yazidis and other ethnic and religious sects.

Rakan Fattah and his brothers, Rayan and Riyadh, now live in a three-room apartment with their mother and their father, who has suffered a stroke and heart attack. Their two sisters fled, one to Iraqi Kurdistan and the other to Lebanon.

Tall, slender and very pale, 37-year-old Riyadh Fattah sits near his aluminum crutches in an unheated room, dressed in layers. A hemophiliac, Riyadh had carried treatment supplies with him from Iraq. However, they are dwindling and the family cannot afford to replace them, says Rakan.

Yet the Fattahs, along with many in their position, have also found help in the Franciscan Missionaries of Mary. Through the sisters, the family has been able to purchase groceries, fix their stove, buy a washing machine and seek medical assistance.

Dedicated to accompanying the most vulnerable, the sisters work to meet needs ranging from material aid — food, utilities, furniture, clothes or heaters — to providing emotional and spiritual comfort where hope flickers and fades. These women of service strive to be messengers of mercy to those plagued by suffering.

In central Amman, a magnificent blue dome flanked by minarets stands out against the morning’s pink horizon, among hills crowded with buildings. A memorial dedicated by the late King Hussein to his grandfather, King Abdullah, the mosque’s distinctive appearance makes it one of the city’s key landmarks.

Such monuments can help newcomers — particularly refugees — become oriented in a new setting. Jordan has a vast and varied refugee population, including tens of thousands of Iraqis, some of whom first fled to the kingdom after the first Gulf war in 1991. While many refugees live in the nation’s well-known camps, the great majority has taken up residence in various urban centers.

Not far from the King Abdullah Mosque, in an unassuming house constructed of the stone typical of buildings in Amman, live the Franciscan Missionaries of Mary. Hailing from around the world — Italy, Korea, Lebanon, Mexico, Poland and Syria — the six sisters in Amman make up a handful of some 6,300 Franciscan Missionaries of Mary serving in 75 countries.

Within its walls, Sister Antoinette Odisho finishes morning prayers.

“When I pray, I feel more strong and peaceful,” says the convent’s superior, a 48-year-old woman with wavy salt-and-pepper hair and piercing green eyes.

“I have to be strong because there are cases I am affected by,” she says of her work with Iraqi refugees and the poor in Jordan. “I feel for them, but I have to manage the situation.”

Born in Hassake, Syria, Sister Antoinette has been in charge of the Amman convent since 2012, taking over for Sister Wardeh Kayrouz, who worked for more than 20 years ministering to refugees and the poor and now serves in Lebanon.

“Since ISIS came in, there has been much more damage to the people,” Sister Antoinette says, calling attention to prevalent chronic issues such as depression.

“Their lives are on hold in exile. They won’t go back to Iraq, saying it’s not safe for Christians, but as refugees they’re barred from working in temporary asylum countries such as Jordan.”

To meet the great needs of this population, Sister Antoinette and her team act both as sisters and social workers. But the dual role does not come easily.

“I get nervous under pressure,” she admits. “I pray for insight into the truth. Wisdom comes with time and experience.” Her experience so far includes apostolates in Egypt, Jordan, Lebanon and Syria. She worked with the Franciscan Missionaries of Mary for years before making her final vows in 2011.

She first encountered the Franciscan Missionaries of Mary at 28. Though she had been considering marriage, she gave up the prospect when she felt called by God to a life of service.

“But I get more than I give,” Sister Antoinette says. “As God sends me to help them, God sends them to help me to grow.”

Sister Brygida Maniurka, 54, from southwestern Poland, agrees.

“During my 26 years in the Middle East, I have given something, but I have received so much more,” says the dimple-cheeked sister.

“I had a normal life before,” she says. “I went to dance clubs every week.”

Yet she had felt the tug of her calling all her life. “From childhood I thought about being a missionary,” she explains.

“I have a passion; I love people.”

Sister Brygida currently serves as the provincial bursar of the Middle East, managing the finances of the Franciscan Missionaries of Mary in Egypt, Israel, Jordan, Lebanon and Syria.

“I am happy to be in my mission and religious life; it changed my personality.” In particular, she credits exposure to Arabic culture with broadening her outlook. “Eastern spirituality is very rich.”

In Syria, Sister Brygida spent seven of her 20 years in Raqqa working with special-needs children, administering physical therapy and speech therapy in collaboration with hospital programs.

“I like to nurture life in another person,” she says. “We need someone to push out the potential inside us.

“When I see children blossom, it makes me very happy. It is the best moment of my life,” Sister Brygida says.

Yet challenges dwell beside triumphs. “The most difficult part,” Sister Brygida says, “is when we receive a family and the need is more than we can offer — when someone has cancer, and we don’t have the possibility to do the operation. And, each family has illnesses due to trauma.”

Six-year old Weaver, a boy with close-cropped light brown hair, recently arrived from Qaraqosh with his family. Weaver does not speak; but he screams, shakes and jumps up and down.

His father, Azhar George Matti, 53, says the boy spoke in Iraq but stopped when the explosions began.

In their tiny apartment, the man sits on a sofa decorated with brown flowers. Above two matching chairs, a small pink rag doll with pigtails adorns the wall.

A teacher in a Catholic primary school in Qaraqosh, Mr. Matti has two other children — a 10-year-old daughter, Lourde, who should be in fifth grade, and another son, 7-year-old Lucien, who should be in second grade. His wife, Rajja, 41, with black hair swept back into a ponytail, seems to stare through the wall as he recounts the family’s journey.

“One day after a liturgy, I saw a priest and five parishioners coming out of the church. ISIS took each one into the marketplace and shot them,” says Mr. Matti.

“I prayed for ISIS, too,” he says, in addition to their victims. “They don’t understand what they are doing.”

The Matti family fled to Erbil by car. For one year, they lived in one room in an empty building. Then, as with the Fattah family, they sold their car and bought plane tickets to Amman.

“It was a very hard experience in Iraq.” Though their current situation is still poor, Mr. Matti speaks positively. “It is good for our spiritual lives now,” he says.

“God will provide.”

Sister Hanne Saad, 71 years old with bushy eyebrows and short white hair, sits beside Weaver. She wraps her arms around him as he shrieks and bounces, rocking him gently.

Born in Hammana, Lebanon, Sister Hanne trained as a nurse and first worked in a small public hospital in southern Egypt. She spent many years in Rome, the hub of the community, working in administration.

“I love this community and its spiritual mission,” she says with a warm smile.

“To be with these people, to listen to them, it gives me joy. If one day, I don’t visit, I don’t feel normal.”

The Matti family met with the sisters a few weeks ago and their needs are being identified and assessed, says Sister Seraphina Moon, 47, from Jeju Island, Korea.

Sister Seraphina’s white scarf highlights her jet-black bangs as she discusses her journey to the religious life.

“I was not Christian,” she says. “I had no belief in God. My family is Buddhist.

“One day I went to a church. I was 21. I dreamed that night of Jesus and Mary. I knew them from pictures, but I didn’t believe in any god. But, I felt something good,” she says.

Sister Seraphina felt her dream was a sign. In Korean culture, she says, dreams are given weight as signs of the future and symbols of good fortune.

Her first response was to play the lottery, she says, but nothing came of it.

After finishing high school in Korea, Sister Seraphina went to Sydney, Australia, for college to study English and marketing. It was there that she met a community of Benedictine sisters and stayed in a guesthouse with them for a month during Christmas.

“I loved that moment,” she said. “I felt maybe I found a way I can live and what God means to me. I wanted to be a sister.”

Initially, her mother did not approve. Sister Seraphina’s father had died young; her mother, at that time 30, supported her four children by running a small soup restaurant. She did not want her daughter to leave.

“Little by little, I learned that this was what I wanted,” she says. “I met the Franciscan Sisters in my parish. My model now is St. Francis. I reflect his life with my life.”

In 2004, Sister Seraphina took her first vows. She was 31 years old. Later, in 2010, she relocated to Jordan and began working as a volunteer with Caritas while studying Arabic. Little did she realize there would follow the worst refugee crisis since World War II.

“The Holy Spirit guided me to my decision,” she affirms.

The Khudhur family arrived in Amman a month ago from Qaraqosh.

“Our Christian neighbors next door were killed,” says Richard Khudhur, 39. “We fled to Erbil with the Peshmerga and stayed for a little over a year, living in an unfinished building in one room.”

At the entrance to the family’s flat, laundry hangs out to dry. Thin mats lie on the floor, and plastic bags line the window to reduce the cold draft.

The family must go out to bathe, as the bathroom has only a small toilet and no bath.

Mr. Khudhur, sporting a goatee and black knit cap, and his wife, Zina, 34, live in the Hashmi neighborhood of Amman with their three children — Elena, age 10; Johan, 6; and Onel, 4. They were given money for their flight from Iraq from the church and friends. They fled with no IDs.

The children were terrified, he says — especially Onel, who started wetting himself.

Elena snuggles between her parents. She is learning English, she says. “I like everything in school. I want to be an engineer.” She beams as she brings out her third-grade report card with perfect grades.

“In the market, ISIS would sell girls. They pick them up off the street,” Mr. Khudhur says. The slave markets in Iraq are used as a way of attracting new recruits to the Islamic State, according to the United Nations.

In the corner, Johan and Onel inflate orange, blue and green balloons. One breaks, and everyone in the room jumps.

The sisters are helping the family by paying their rent and providing basics — food, blankets and mattresses. Sister Seraphina says they will buy a washing machine, too.

As with the Fattahs and the Mattis, the Khudhurs, once middle class, have fallen into poverty. They are trying to survive far from home with little hope, dependent on good people such as the sisters to provide what they themselves cannot, just to get through the next day.

“The Iraqis have a faith in God that is astounding,” Sister Seraphina says, “after all the tragedies of war. It makes me pray to be a better religious.”

Sister Antoinette shares the same desire to effect the greatest good. “I pray to God to send me to the most vulnerable people to help.”

Formerly with the Associated Press, Diane Handal covers the Middle East for ONE.