roomful of people in Norway

Emphasis mine.

This is going to sound a little odd but bear with me. I see these people here all the time, ie. angsty teens (for the most part) who are between cultures and have no proper sense of belonging to either Norway or any other country and they don't really even have a language as they speak brokenly in every one.

The cause is, and this is just my own personal speculation, a law that allows for family reunification. This causes us to get first-generation immigrants every generation as young men often fetch wives from their home countries and then bring over the wife's family as a bonus. Additionally, our integration policies are all carrot and no stick so we have managed to create ghettos of low-income areas where these people congregate. Young, disenfranchised youth lose a sense of purpose and feeling of control over their own lives so they look to stuff like this and the relatively few imams who teach it.

These youth, however, are typically not your radical muslims. They're just there because it's something to do. They act all pious on fridays and then they go out to party and drink like everyone else. There are some exceptions of radical youth but they are widely ridiculed even in their own environments. The much much much larger problem is that we have adults who preach this sort of nonsense and we don't really know how to stop it because freedom of speech is a big thing here just like in every other civilized nation. Doubly so for religious speech because we had a state church for the longest time and because of that a sense of ingrained sensitivity and tolerance for people's religious beliefs or lack thereof has been ingrained in us. Still, if this was actually a practical problem, we would actively combat it but it just isn't. This isn't Sweden.

tl;dr - The real problem here is a failed immigration policy and a growing group of disenfranchised youth this has created. These people are our version of chavs.