When Vallat returned to France in 1994, he began visiting a Salafi mosque his GIA friends had recommended. Salafism, an ultraconservative, fundamentalist strain of Islam that aspires to emulate the Prophet Mohammed and return to the religion’s supposed original ways, has been known to breed jihadists. At the mosque, he was told that modern-day Islam was a domesticated product of colonization, and that true Islam was that of combatants, of sacrifice, of blood. Anyone opposing the jihadists must be annihilated, he was told. He read the Koran and began learning Arabic.

Several months later, Vallat left France for an al-Qaeda base camp in Taliban-controlled territory in Khalden, Afghanistan, where he trained alongside Chinese, English, Yemeni, Malian, Turkish, Tunisian, Algerian and Filipino fighters in the “wild west,” as he called it: no state, no laws, just tanks, guns, and explosives. “There, they think only about death—how to kill and who to kill,” Vallat said.

After 10 months of training, the 22-year-old Vallat returned to France to stay with an Algerian friend he met at a Salafi cell in Chasse-sur-Rhône, a small town outside his hometown of Lyon. Working as a junior al-Qaeda operative, he prepared to return to Bosnia as an arms dealer and die for Allah “like the Americans in Normandy.” But on August 29th, 1995, just a month after a bomb exploded inside a Paris metro killing eight and injuring 100, French authorities raided the cell and arrested Vallat. They were so surprised to find a French native that his mother was asked to confirm that he was not an undocumented Algerian. He was sentenced to five years in prison for engaging in terror activities.

At first, Vallat was enraged. He considered himself a victim of colonial France’s anti-Islamic system. But, isolated from jihadi propaganda and his network of friends, he was forced to interrogate his own ideology, he said. He began to read two books a week and enrolled in university courses, studying French literature, history, geography, philosophy, and the Greek classics. Reading Machiavelli and Rousseau gave him a new political idea—what he later referred to as the “gift of humanism,” where the potential for human goodness is regarded as a more important force than anything divine. “I started to understand that all humans … can make a choice to believe in God,” Vallat, now 45, told me when we met at a sun-soaked café in central Lyon. “We can decide what we want, and the majority of our choices can be made to benefit us here on earth. Really, it shocked me.”

By his fourth year in prison, he was “completely deprogrammed,” he said. He claimed he never returned to jihad, and there’s no evidence that he did. GIA radicals issued a fatwa against him in 1995 when he began to speak out against them; last year, the Islamic State issued a second one via Facebook.