"The global picture is of the community left alone with no one from the state or authorities really wanting to know what's happening inside, letting people organize themselves — for good things and bad things," Moniquet added.
Molenbeek provides a grim lesson of what is happening in other parts of Europe, according to Adam Deen, a former British radical who is now part of U.K. anti-extremist organization the Quilliam Foundation. Muslims are increasingly being offered a very narrow interpretation of Islam — Wahhabism, the strict sect aggressively promoted by Saudi Arabia throughout the world, he said.
"What this does is create a sense of alienation from the place you were born and brought up. You begin to hate the society you were brought up in," said Deen, who says he still practices Islam but has abandoned extremism. "Now what happens is that any Muslim who wants to be active within the Muslim community, the default position is Wahhabism or a varied form of it."
He added: "Wahhabism creates a binary outlook on the world. That kind of indoctrination [which preaches that] all non-Muslims are non-human make it is quite easy to put a bomb in a public place."
With no "counter-narrative," a small number of adherents find themselves at ISIS' door, Deen added. Indeed, there were believed to be around 1,200 French ISIS recruits in Syria and Iraq in by the end of 2014, according to a January study by the International Center for the Study of Radicalization and Political Violence. Belgium sent some 440, the report said — the highest per capita of any European nation. Germany and the U.K. both sent more than 500.