On a recent Sunday morning in Monrovia, the capital of Liberia, a few dozen people gathered in a tin-roofed church to hear a former warlord preach. His name is Joshua Milton Blahyi, but most Liberians still know him by his nom de guerre from the nineteen-nineties: General Butt Naked. A burly forty-five-year-old with a head shaped like a cannon shell, Blahyi took the stage wearing black dress pants and a cream-colored shirt. He has delivered sermons across West Africa about the power of forgiveness and the perfidy of Liberian politicians, but one of his favorite topics is himself. “In South Africa I was privileged to preach to parliament,” he told his congregation. “Hallelujah! It can happen to you!” A slip of paper fell from his Bible, and a worshipper hurried to pick it up. “Keep it as a souvenir,” Blahyi said.

In 1980, Samuel Doe seized the Presidency of Liberia in a coup. Blahyi claims that he later became Doe’s spiritual adviser, and that he used witchcraft to help Doe win a second term. (Doe also used more mundane methods, such as burning his opponents’ ballots.) On Christmas Eve, 1989, Charles Taylor, a former Liberian government official, invaded from Ivory Coast with a hundred soldiers, and the country plunged into civil war. There was a ceasefire in 1996, and Taylor was elected the next year. Then, in 1999, another rebel group invaded from Guinea, sparking a second conflict, which lasted until Taylor was ousted, in 2003.

During the nineties, most of Liberia was controlled by rival militias. In the bush, they battled for control of diamond fields and gold mines; in Monrovia, they fought gun battles in the streets. Reporting to the militia leaders were dozens of rebel commanders, many of whom adopted outlandish names: Chuck Norris, One-Foot Devil, General Mosquito, and his nemesis, General Mosquito Spray. Blahyi was active for about three years, and, as General Butt Naked, he led several dozen soldiers—the Naked Base Commandos—who fought mostly in Monrovia. Many of the soldiers were children, and, like their commander, they often wore nothing but shoes and magic charms. In a distorted emulation of animist tradition, Blahyi claimed that this made them “immune to bullets.”

On April 6, 1996, in Monrovia, Taylor’s soldiers attempted to arrest the leader of the militia with which Blahyi was affiliated. Blahyi and other rebel commanders fought back, leading to one of the most ferocious battles of the war. About half of Monrovia’s residents were displaced. As the city erupted into chaos, a bystander saw Blahyi standing naked atop a truck, holding an assault rifle in one hand and a man’s severed genitals in the other.

All told, some two hundred thousand people were killed in the Liberian civil war. When hostilities finally ended, in 2003, the peace agreement called for a Truth and Reconciliation Commission. The group convened three years later, in a compromised state: none of the members had served on such a commission before, and they lacked the power to bring binding charges. Still, the proceedings were broadcast live, across the country, on radio and TV. Blahyi was the first former warlord to testify. Wearing an immaculate white dress shirt, he spoke with surprising candor. “I want to say sorry,” he said. As photographers’ cameras clicked in the gallery, he hung his head and appeared to weep. “Everything I was doing was devilish, was wrong, was inhuman.”

One of the commissioners asked Blahyi to estimate the number of people he had killed.

“If I were to calculate—if you’re talking about April 6th, or throughout the war, or every evil I have done, it should not be less than twenty thousand,” Blahyi said.

During the course of two hours, he described his role in the war. He said that he used human sacrifice and cannibalism to gain magical powers. “I needed to make human sacrifices to appease the said deities, or the gods,” he said. “Every town I entered . . . they would give me the chance to do my human sacrifices, which included innocent children.” He then told the story of his conversion to Christianity, which took place shortly after the April 6th battle. The commissioners, apparently enthralled by Blahyi’s account, challenged few of his claims. One of them commented, “You have a lot of good leadership qualities.”

Blahyi’s testimony was front-page news in Liberia. Strangers hugged him on the streets of Monrovia, and journalists came from all over the world to interview him. The Daily Mail ran a profile under the headline “Face to Face with General Butt Naked—‘The Most Evil Man in the World.’ ” Vice featured Blahyi in a lurid travel documentary called “The Vice Guide to Liberia,” which has been viewed more than ten million times on YouTube. Bojan Jancic, the pastor of an evangelical church in the East Village, saw the video and later became one of Blahyi’s benefactors. Blahyi has written five books; a memoir titled “The Redemption of an African Warlord” was published in 2013 by a small Christian press. In the foreword, Jancic wrote, “Not since the conversion of Saul of Tarsus on the Road to Damascus have I ever heard a conversion story more radically compelling.”

In the tin-roofed church, Blahyi neared the end of his sermon. The previous night, he had watched a documentary about Whitney Houston. “She was one of the world’s greatest pop stars,” he said. “But what struck me was Kevin Costner, one of her co-stars. He said, ‘She suffers a complex. She always talk in her mind: “Will I really be accepted by the people?” ’ Even me, that everyone look at today as a wonderful preacher—as a brave man who did all those things in the past, as a hero—I still suffer.”

Blahyi stalked the aisle, beating his chest, his shirt translucent with sweat. “I am a bit different from many people,” he said. “Even though it is impossible, I still know that Jesus love me.” He wiped his face with a white cloth. “When Jesus met me, I was wicked on the street and destroyed the life of an innocent child, and He called me His son!”

Not long ago, I spent a week with Blahyi in New Georgia Estate, a suburb of Monrovia. His house is mustard-colored and modest, with a flickering power supply and no running water. One morning, Blahyi decided to play in a pickup soccer game. He donned a white jersey and sat on a couch in the living room while his teen-age nephew, Emmanuel, who serves as his factotum, laced up his cleats. Then Ernest Nelson, one of Blahyi’s several half brothers, drove him down the cratered dirt roads of the neighborhood in a silver S.U.V. Blahyi leaned out the window, grinning and waving at pedestrians like a visiting dignitary.

The soccer game was already in progress, but Blahyi jogged onto the field without waiting for a substitution. He was one of the few players with his own shoes; the others shared, swapping during substitutions. A torrential rain began to fall, turning the field into a boggy sump. Blahyi jumped for a header, missed, and fell in the mud.

Near the end of the game, with the score tied, he planted himself in front of the opposing goal. He was flagrantly offsides, but no one stopped him. He captured a loose ball, pivoted, and levered the ball past the goalie. Minutes later, he scored again. When the final whistle blew, he jogged to the center line and stamped victoriously in the mud.