One afternoon two summers ago, during Ramadan, Moazzam Begg and his daughter drove to London from their home in Birmingham. The traffic was heavy. It was twilight by the time they reached Malet Street Gardens, a sunken park in Bloomsbury, where a Muslim charity had set up a tent and invited all comers to break the fast. More than a hundred people sat cross-legged on plastic tarps, passing bowls of dates and steaming boxes of rice and lamb. The charity had billed the gathering as apolitical, but this was complicated by the choice of Begg as speaker. He had spent nearly two years in the US prison camp at Guantánamo Bay before being released without charge. He is 47 years old, trim and wiry, with a gray-streaked beard. On that day he dressed casually, in an untucked button-down shirt and slip-on shoes. Some see Begg as a persecuted victim, others as a jihadi propagandist whose left-wing sympathizers are naive dupes. Begg’s own rhetoric resists easy binaries. He took the microphone and said, “As you’re breaking your fast, just remember, there are brothers and sisters imprisoned in prisons and dungeons across the globe. Whether they’re Muslims or not. Held without charge or trial. What happened to the core British value of believing in the rule of law? You can understand that governments of third-world despotic regimes have been doing this. But how is it that Britain and America have been doing this?”

Political Islam is seen as a problem by the neoliberal West. The norm of multicultural tolerance demands empathy and accommodation for newcomers, in exchange for an implicit promise not to engage in overly disruptive politics and to confine religious practices to the private sphere. Many Muslims, however, see their religion as an inherently political practice and are unwilling to trade it away. This is especially true in Western Europe, where, compared with their American counterparts, Muslim immigrants tend to arrive with fewer financial resources and greater religious devotion. In Britain, Muslim communities are prone to forming enclaves, partly in reaction to the reluctance of their new homeland to fully assimilate them. Looming over them are centuries of accumulated grievances, the destruction caused by the Iraq War, the legal atrocities of Guantánamo, and the cloud of suspicion that any young man from one of these communities could turn into a suicide bomber. The British government has spent more than a decade putting these young men under intense surveillance. To identify publicly with any jihadist cause is now liable to trigger an escalating regime of legal sanctions, from surprise visits by intelligence agents to intensive airport searches to house arrest. Security is the imperative used to justify these measures, but it is unclear whether they have accomplished much beyond creating a permanent class of angry and unassimilable young men.

Two years after his release from Guantánamo, Begg wrote a memoir entitled Enemy Combatant. The book recalls his first visit to a jihadi training camp, in the mountains of Kashmir. “To me, jihad is like a drug I’m allowed to take, and I always come back for more,” Begg recalls the camp’s emir telling him. This was in 1993, before the Taliban took Kabul, before the September 11 attacks, before the wars in Afghanistan and Iraq, and before the lower-intensity guerrilla warfare that continues to smolder in the present landscape of drone strikes, suicide bombings, and mass shootings. In 1993, jihad was not such a dirty word. “People went to Bosnia or Afghanistan,” says Saghir Hussain, a lawyer who works with Begg. “They died, or they didn’t. The ones who didn’t came back.”

Since his release from Guantánamo, in 2005, Begg has devoted himself to what he calls “the jihad of the tongue,” pushing back on the notion that Western governments have superior values to match their superior weaponry. He makes his case like a gentleman. Instead of pounding the table, he asks unsettling questions. Through appearances at university debating societies, town councils, and on the BBC, Begg has built a bridge between two British constituencies, antiwar liberals and the pro-jihad wing of British Islam. John Rees, one of the leaders of Britain’s Stop the War Coalition, told me that he was impressed by Begg’s “moral authority, from having been locked up at such a hideous place and having not been proven to have committed a crime. His composure and self-possession come across to anyone who meets him.”

Begg works closely with Cage, a British advocacy group. “People say that we represent terrorists, which we do,” says Asim Qureshi, research director for Cage. “Terrorists, as in people who have participated in acts of political violence or who have been promoting them, and so forth. There is no one who we won’t represent, if they have been subjected to a lack of due process.” For Begg, Cage’s role is to stand up for the rights of an oppressed religious minority. “The Shining Path, the Tamil Tigers, the Michigan Militia, the Unabomber — I’d like to see them all in Guantánamo,” he told me. “But none of them are. It’s only Muslims in Guantánamo. Why? Very clearly the war on terror is a war against Islam, in the minds of some people.”

After dinner, Begg sang the call to prayer, gave another talk, and spent a few minutes chatting with a crowd of admirers. Begg is a compelling speaker, but in smaller groups he is reserved, almost cold. When he does speak, he prefers to talk about history, foreign policy, and Islam, not himself. At Guantánamo, he writes in his memoir, detainees did not probe into the circumstances of one another’s capture.

We were a few blocks away from Tavistock Square, where, during the morning commute of July 7, 2005, Hasib Hussain, an 18-year-old student from Leeds, detonated a bomb on a bus, killing himself and thirteen passengers. Years later, the country was still dealing with a steady drumbeat of threats. “Jihadis ‘Staying in UK to Plot Attacks,’” read a recent headline from the Evening Standard. ISIS-friendly Twitter accounts were posting images of ball bearings, nails, and bomb-like packages with the hashtag #LondonAttacks. Several hundred people had gone to Syria to join ISIS. In late June 2015, more than a thousand British police participated in an exercise called Strong Tower, a simulated Charlie Hebdo–style mass shooting. David Cameron, then the prime minister, was pushing measures that would expand counterterrorism into “counter-extremism,” by cracking down on Muslim groups that pushed an antigovernment line. “The root cause of this threat is the poisonous ideology of extremism itself,” he said in 2015, three days after ISIS carried out a coordinated attack at the Bataclan and other public spaces in Paris. “Those who promote extremist views — even if nonviolent themselves — are providing succor to those who want to commit or get others to commit violence.” Cameron wanted more surveillance, more airport detentions, more authority for the government to sanction a wider group of people with less of an evidentiary predicate. Cameron singled out Cage by name and attempted to pass an Extremism Bill that would have given the government the authority to issue Banning Orders effectively outlawing certain groups, as well as Extremism Disruption Orders to ban individuals from using the internet. The bill failed, due in part to how hard it is to codify a working definition of extremism.