The attacks in Brussels, on the heels of those in Paris and San Bernardino, Calif., have stoked an already white-hot debate about Islamic terrorism in the United States. Many in the West, including the two Republican presidential front-runners, Donald Trump and Sen. Ted Cruz (R-Tex.), urge a campaign that targets Muslim communities more directly, searching for those who might be prone to religious extremism and thus terrorism.

But the recent bombings in Europe are being perpetrated by a new generation of terrorists who are upending our previous understanding of what motivates such people and how to find and stop them. To put it simply, today’s terrorists are not religious extremists who became radicals but rather radicals who became religious extremists. The difference is crucial.

Look at the two brothers who planned and executed the Brussels bombings, Ibrahim and Khalid el-Bakraoui. Born into a working-class immigrant family (from Morocco), they were not particularly religious and early on chose a life of crime. By their mid-20s, the two had participated in carjackings and armed robberies. Ibrahim was sentenced to nine years in prison for attempted murder; his brother, five years for armed robbery. And then, it seems, in prison or after, their path to jihad began.

Their story is strikingly similar to those of many of the other terrorists in Belgium and France. Few were devout Muslims. Abdelhamid Abaaoud , the ringleader of the Paris attacks, regularly used drugs and drank alcohol, as did many of his comrades-in-arms. In August 2014, the New Statesman reported on two British jihadis, both 22, who, before leaving Birmingham for Syria, bought copies of “Islam for Dummies” and “The Koran for Dummies.”

A remarkably thorough study by scholar Rik Coolsaet for Belgium’s Egmont Institute tries to make sense of this new wave of jihadis and distinguishes them from previous ones, such as those who turned to al-Qaeda before 9/11. The average age of a European jihadi from 2001 to 2009 was 27.7. Today, it is close to 20. A decade ago, it took years of religious indoctrination to turn people into jihadis. Today, the decision to join the Islamic State is usually sudden and impulsive.

Consider one telltale difference. Al-Qaeda and its ilk issued fatwas with detailed critiques and politico-religious demands. What are the demands behind the Paris and Brussels attacks? Writing about these young French jihadis, Olivier Roy, a French scholar of Islam, points out that almost none have a background in political activism (say, Palestine), fundamentalist Islam or social conservatism. “Their radicalization arises around the fantasy of heroism, violence, and death, not of sharia and utopia,” he writes. The Islamic State is the ultimate gang, celebrating violence for its own sake.

These young men — and some women — are usually second-generation Europeans. In fact, Roy points out that often they are revolting against their more traditional, devout immigrant parents. They are unsure of their identity, rooted in neither the old country nor the new. They face discrimination and exclusion. And in this context, they choose a life of rebellion, crime and, then, the ultimate forbidden adventure, jihad.

These circumstances would explain why Belgian Muslims make up a disproportionate share of Islamic State volunteers — which is otherwise a puzzle. The Egmont paper notes that the gap in education and unemployment between natives and immigrants is higher in Belgium than anywhere else in Europe. Fifteen percent of native-born Belgians live below the poverty line, compared to a staggering half of Belgians with a Moroccan background. In addition, Belgium has a particularly poor record of assimilation, because it has its own crisis of identity, torn between two cultures, Flemish and Walloon.

Why are these findings so important? They paint a picture of a new kind of terrorist, one who is less drawn into terrorism through religion but rather who has chosen the path of terror as the ultimate act of rebellion against the modern world — and who then finds an ideology that can justify his desires. Radical Islam provides that off-the-shelf ideology, easily available through the Internet and social media. But it is the endpoint in the chain, not the start.

This still means that Muslims have to battle and eradicate the cancer in their midst that is radical Islam. But it does suggest that for Western law enforcement, bugging mosques, patrolling Muslim community centers and even fighting fundamentalist Muslims might be focusing attention in the wrong direction — if the goal is to find terrorists. Those people might instead be in the bars, drug alleys, unemployment lines and prisons, getting radicalized before they get Islamized.

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