I have the impression, correct me if I am wrong, that the young Muslim men in Europe are not especially religious. They are angry, hostile to the greater culture, disaffected, and largely unemployed. Their object seems to be destruction of Western culture.
I think the European welfare culture feeds this growing cancer on the body politic.
I read a very instructive article about the cites (French government housing) that exist outside every French city. They are a breeding ground for hostility and terrorism. They are fed and supported by the French taxpayer.
By the time the Europeans awake to the danger they have imported and nurtured, it may well be too late.
If you ever go to Paris, do not: 1) take the train into the Gare Nord from DeGaulle Airport; 2) get off at the Les Halles metro stop; 3) be in the Metro after closing at 12:30 pm. All of these locales are plagued by angry young Muslims looking for, and often causing trouble.