Martyrs in the Time of the Charity Selfie

In an age when giving can be as easy and fun as a YouTube video and a bucket of ice, the two Americans who contracted Ebola in Liberia remind us of a long line of missionaries and Christian aid workers who have labored out of the limelight at grave personal risk.

Historians tell us that when a great plague wreaked havoc in the Roman Empire during the third century A.D., many pagans fled. The followers of Jesus (sometimes called Galileans) tended to the sick and dying, at times paying for their compassion with their lives.

Even then they were sometimes rewarded with derision. Julian, the last pagan emperor of Rome—known to history as "the Apostate"—later mocked the good works of Christians as a way of increasing their flock: "[W]hen it came about that the poor were neglected and overlooked by the [pagan] priests, then I think the impious Galileans observed this fact and devoted themselves to philanthropy."

Yet mockery and misunderstanding are the least of the concerns for missionaries in the post-9/11 world. As the scary Ebola cases of Kent Brantly and Nancy Writebol demonstrate, sharing the good news in word and deed can be life-threatening.

Dr. Brantly is a physician who was infected while volunteering with the Samaritan's Purse team responding to the Ebola outbreak at the mission hospital in Monrovia, Liberia's capital. Mrs. Writebol came to Liberia with Service in Mission, or SIM, and was infected while serving as a hygienist decontaminating those entering or leaving the isolation ward. Mr. Brantly and Mrs. Writebol were released from an Atlanta hospital this week.

Despite their ordeal with an often fatal disease, they are fortunate by comparison to many who went before them. In 1894 two of the three founders of Service in Mission died after contracting malaria from mosquitoes. Such were the dangers, in fact, that many missionaries to Africa once elected to bring coffins along with their pith helmets.

Such health risks, though still considerable, have lessened, thanks to improved medical care and the ability to evacuate if trouble arises. According to Wheaton College's Brian Howell, more and more of today's cross-cultural workers, as missionaries are also called these days, are short-term technical specialists. They can be deployed quickly to international hot spots and, with luck, just as quickly removed.

A more immediate threat to missionaries now comes from religiously motivated violence—kidnappings, terrorist attacks and war. Scott Moreau, the editor of EMQ, a professional journal for missionaries, says that "security issues are significantly more challenging" than they were a generation ago. And now, he told me, people are at risk "from exposure as missionaries based on Internet research to physical targeting—and, at times, death—by radical groups of all stripes."

Expanding the definition of what constitutes missionary service has also raised the stakes. Charley Warner, a missionary serving in Central Europe, points to the International Justice Mission, a Christian-based group which seeks to rescue women trapped in sex trafficking.

"This is a popular type of mission work," Mr. Warner told me. "However, it's extremely dangerous. [Rescuers] face powerful mafias who stand to lose a lot of money when they lose their 'slaves.' "

Despite better precautions in modern times, premature death is always possible for missionaries serving in the world's hard places. SIM missionaries were murdered in Ethiopia in the 1920s and '30s. Several in Nigeria died of Lassa fever in 1969. Ethiopian guerrillas killed American missionary Don McClure in 1977.

During the 1990s, New Tribes Mission, which seeks to start churches among tribal groups with little access to the Christian faith, saw two of its missionaries murdered by leftist rebels in Colombia. Three more people from New Tribes Mission were kidnapped by rebels demanding $5 million in ransom. Their whereabouts remain unknown. In 2001 Christian missionary Veronica Bowers and her daughter, Charity, died when Peruvian authorities shot down the plane they were in, mistakenly believing it was part of a drug-running operation.

Knowing the inherent risks their workers may face abroad, most agencies provide missionaries with crisis contingency training and a detailed evacuation plan. But many missionaries balk at the thought of leaving behind co-workers and those they feel called to serve. Before Nancy Writebol was infected, she and her husband, David, declined an offer from their church to come home.

As Mr. Warner points out, however, many do not have such a choice. Most Christian martyrs today are not Americans. Non-Westerners continue to bear most of the risk, having no contingency plans on which to rely. Like the Christians in the Roman Empire, they must stay the course, no matter what.

Mr. Guthrie, a Christianity Today editor at large, is author of "Missions in the Third Millennium" and "God's Story in 66 Verses," due in January from Thomas Nelson.