It wasn’t as if God's voice boomed through sun-parted clouds, telling Kent Brantly to move his family to Liberia.
Still, the young doctor said, the call was clear.
It echoed through the congregation where he was raised, Southeastern Church of Christ in Indianapolis.
Standing before the church community in July 2013, months before he left for Africa, Brantly said he heard the call in the teachers who urged him to memorize Scripture and the neighbors who funded his first mission trip years ago.
He saw it in the aunts and uncles who spent their vacations running Bible camps, organizing youth groups and serving missions themselves in Africa.
“It may not seem like much,” Brantly said in an emotional address to the Southeastern congregation, “but when you connect the dots you see a grand design that God has used to draw my life in a certain direction.”
For Brantly, that meant serving a two-year medical mission in Liberia with Samaritan’s Purse, a Christian relief organization. But in a grim twist that garnered international headlines, the 33-year-old contracted Ebola while treating patients suffering from the deadly disease and was airlifted back to the United States.
Brantly and a fellow missionary, Nancy Writebol, who was serving with SIM, another Christian aid organization, are being treated for the disease at Emory University Hospital in Atlanta.
After Liberia's outbreak began in March 2013, Writebol volunteered at a hospital Monrovia, where she disinfected doctors and nurses working with patients stricken by the disease.
Despite their weakened health, their trust in God remains strong, family members said.
“Mom is tired from her travel, but continues to fight the virus and strengthen her faith in her Redeemer, Jesus,” said Jeremy Writebol, Nancy’s son.
On Friday, Brantly said that he felt a spiritual serenity even after learning his diagnosis.
“I remember a deep sense of peace that was beyond all understanding,” he said. “God was reminding me of what he had taught me years ago, that he will give me everything I need to be faithful to him.
Though Brantly's wife and children had been in Liberia with him, they had returned to the United States when he became ill.
In addition to the American missionaries, a nun and a priest from Spain who worked in Liberia also contracted Ebola, two more victims in an outbreak that health officials describe as the largest and most complex in the history of the disease.
As of Saturday, 961 people have died, nearly all in Liberia, Sierra Leone and Guinea, where more than 1,770 cases have been reported, according to the World Health Organization.
Heroic or foolish?
In the United States, much of the attention last week focused on the missionaries, who knowingly put themselves in harm’s way.
Christians have long debated the effectiveness of missions, with some arguing that they can, at times, cause more harm than good – both to missionaries and the people they are trying to help.
But rarely has the debate ranged as far afield of Christian circles or become as bitterly divided as it has since the American missionaries' return to the United States.
Prominent Christians, such as R. Albert Mohler Jr. and Russell Moore, called Brantly and Writebol heroic.
The missionaries knew the risks of contracting Ebola but worked with patients, doctors and nurses to try to contain the outbreak, the evangelicals said.
On the other hand, real estate mogul Donald Trump tweeted that people who travel to foreign countries to help are "great" but “must suffer the consequences” of their actions.
Conservative commentator Ann Coulter was even more unsympathetic, saying Brantley’s health status had been “downgraded to ‘idiotic.’”
“Why did Dr. Brantly have to go to Africa?” Coulter wrote. “The very first ‘risk factor’ listed by the Mayo Clinic for Ebola - an incurable disease with a 90 percent fatality rate - is: ‘Travel to Africa.’”
Nancy Writebol's husband, David, who remains in Liberia, answered the critics on Friday.
Writebol said he knows that some think missionaries like his wife are "foolish, or worse," to "put everybody in danger by going" to places like Liberia.
"But it’s that very calling," he said, according to the Atlanta Journal-Constitution, "that demonstrates the characteristics, the great things that Christ has done for humanity. He left heaven and he came to a place of suffering and trouble and went about doing good.”
The Great Commission
Besides the personal pull described by missionaries like Brantly, for centuries Christians have followed a more general call to spread the Gospel through word and deed. Known as the Great Commission, it began when Jesus told the apostles to “go and make disciples of all nations.”
Since then, millions of believers – from Baptists to Mormons to Jehovah’s Witnesses - have stuffed scriptures into suitcases and preached the Gospel in nearly every corner of the globe.
For centuries, serving those missions meant spending decades abroad, learning a culture and its language, and trying, with varying degrees of success, to convert native peoples to Christianity.
But short-term missions - often defined as less than two years - exploded in the 1970s and ‘80s with the advent of cheap and safe travel, scholars say. For evangelicals in particular, mission trips have become almost a rite of passage. In his 33 years, Kent Brantly had already served missions in Haiti, Honduras, Kenya, Tanzania, Uganda and Nicaragua.
In doing so, Brantly is one of an estimated 1.6 million Americans adults who embark on short-term mission trips to foreign countries each year, according to Princeton University sociologist Robert Wuthnow.
If domestic missions and Christians under 18 were included, that number would rise to about 2.4 million, said David Armstrong, executive director of Mission Data International.
It’s an indication of how seriously Christians take Jesus’ call to reach “all nations,” a task to which they bring ever-increasing technical sophistication.
The Center for the Study of Global Christianity at Gordon-Conwell Theological Seminary in Massachusetts, for instance, keeps tabs on the precise percentage of the world’s population who have been “evangelized.”
As of mid-2014, about 71% of the world has heard the Gospel through personal preaching, radio, television books or other media, the center says.
But not all missions are about evangelizing.
There are basically three types of missionaries, said Albert W. Hickman, a researcher at the Center for the Study of Global Christianity: those who preach, those who do good works, and those who do both.
SIM, which Nancy Writebol joined in 2013, belongs in the last category.
'Do you mind if I pray with you?'
Originally know as Sudan Interior Ministry, the Christian group has been active in Africa since 1893, when two young Canadians and an American set out to preach the Gospel in sub-Saharan Africa.
Within months, the men contracted malaria. Two died, but one survived and went on to help lay the groundwork for the modern SIM, which now stands for the more general Serving in Mission.
“Even early on, our people were willing to sacrifice or to die for their faith,” said George Salloum, SIM USA’s vice president of finance and operations.
More than 1,600 SIM missionaries now work in 60 countries.
The majority are recruited online, a process that starts with questions for applicants like: Do you share your faith with others? Is prayer a regular part of your life? Are you disciplined, accountable? Have your really thought about how hard being a missionary will be?
The list of missions SIM offers is extensive – from a Bible school teacher in Mongolia to a water engineer in South Sudan. The group also sends medical professionals to mission hospitals and clinics throughout the world.
Before they travel, missionaries go through cross-cultural training, learning, for example, how close should they stand while taking to someone and how different cultures greet strangers.
Missionaries also are also trained in their most critical skill, Salloum said: How to provide practical help while simultaneously spreading the Gospel.
For instance, when a person suffers from an illness or injury, the medical missionary will approach and ask if they can help. “The missionary just shares something ... and then sometimes they’ll say, ‘Do you mind if I pray with you?’”
“People will say, ‘Why are you doing that?’ And we tell them that’s what Christ did,’” Salloum said. “It’s a natural transition – someone who has a physical need then to have a spiritual need.”
That's precisely what Nancy Writebol did in Liberia, said the SIM executive. “She talked to children, she shared the Gospel. She was just available, there for the people. That was her world.”
Writebol and her husband are originally from Charlotte, North Carolina, and have two adult sons, according to SIM.
In Liberia, before the outbreak, Nancy served as a personnel coordinator, guiding new missionaries as they entered the West African country. She also volunteered on the staff of ELWA hospital, where David Writebol worked as a technical services manager of the 100-building complex.
"We aren't going to stop our ministry – we believe we can serve wherever God sends us," David Writebol said on Friday.
Samaritan’s Purse, the Christian relief organization Brantly worked for, declined to speak to CNN.
David Armstrong, from Mission Data International, said the organization, which is headed by Franklin Graham, focuses chiefly on emergency aid, particularly the physical needs of native populations. But they also try to tend to spiritual needs, which means providing Bibles and setting up prayer meetings.
“They are sharing the Gospel, but it’s more of a one-on-one, person-to-person thing,” Armstrong said.
Good works (without preaching the Gospel)
One of the world's largest faith-based organizations doesn't even like the "missionary" label, according to a spokesman, because of the word's association with proselytizing.
Though Catholic Relief Services says it is motivated by the Gospel to embody Catholic social and moral teaching, it does not preach to the people it helps.
In fact, you don't even have to be Catholic to work for Catholic Relief Services. Among its 4,500 workers are many Muslims, Hindus and members of other religions, said Bill O’Keefe, the organization’s vice president of advocacy.
“We assist people of all backgrounds and religions and we do not attempt to engage in discussions of faith," O’Keefe said. “We’re proud of that. We like to say that we assist everybody because we’re Catholic, we don’t assist people to become Catholic.”
Founded in 1943, CRS has 4,500 workers more than 60 countries, including 250 CRS workers in Sierra Leone, Liberia, Guinea and Nigeria, the West African nations hit hardest by the latest Ebola outbreak.
“The biggest obstacles they’re facing is misinformation,” said CRS spokesman Michael Stulman, who was recently in Sierra Leone. “The people believe that Ebola is a curse or that it’s a lie made up by authorities.”
Meredith Dyson, CRS’s health program manager in Freetown, Sierra Leone, said her job is to get the public to stop believing those myths.
Some Liberians, for instance, believe that a soft drink can cure the disease, or that Ebola is a nefarious plot concocted by nongovernmental organizations and the government.
“People say don’t go to the hospital, you won’t come back because healthcare workers are injecting people and killing them,” she said.
“Every myth is born of some kind of truth – it is partly what they’re seeing – people are going to hospital and not coming home.”
Dyson, 31, studied public health at Johns Hopkins University in Baltimore where she met people who worked for CRS. Though not Catholic herself, Dyson said the church's teachings on human dignity and social justice resonated deeply with her.
Describing the recent Ebola outbreak, Dyson's voice breaks as she recalls two CRS colleagues - both Africans - who died will trying to help others.
“The people who work in this setting are close knit,” she said. “They become your family. It can be really hard.”
Back in the United States, sitting in an isolation room at Emory University hospital, Brantly said he didn’t move to Liberia to fight Ebola, but that it became necessary after the outbreak there.
He said he held the hands of countless patients who died of the disease, and still remembers each of their faces and names.
Brantly's mission may not have been what he imagined when he spoke to Southeastern Church of Christ those many months ago, but his focus remains the same: going wherever God leads.
“One thing I have learned," Brantly said, "is that following God often leads us to unexpected places.”