It's all a matter of perception. People pretend like this is a terror attack, when it's way more likely it was just some asshole that went stabcrazy. Similar thing with the attack in Reutlingen a few days ago.
Yeah, islam and culture has something to do with it, but in those cases, but it's a bit much to call it a terrorist attack.
As for "legit" terror attacks like what happened in Paris, Brussels, etc. I would assume it's a cultural identity problem. Basically, certain people feel uncomfortable with their social surroundings (old fashioned cultural and vague religious ideas vs liberal values). In this conflict they fall prey to hatefilled, but convenient rhetoric ("It's not your fault! It's the devil's debauchery that is alive in western culture!"). Once radicalization starts, it's hard to stop. The more these people clash with their surrounding people (family, coworkers, etc), the more the group they have to fall back to for support is some group of radical assholes.
So at a certain point, you have inner influences and outer influences that speed up this process and in the end, some asshole grabs a gun or bomb and heads to some public place to kill some people.
Obviously, the problem lies within islam that has an issue with Imams and so called experts (like the guy that had some sort of Anti-gay symposioum shortly before Orlando) that teach incredibly anachronistic, hatefilled bullshit and an muslim community that either ignores or partakes in this charade.
I blame the wishy-washy attitude of the so called "moderate muslims" for a lot of this nonsense. When some asshole kills a couple dozen people in the name of your religion, going "well, he doesn't speak for me!" is not enough as long as hate and intolerance is taught in many religious groups - with the connivance of "moderate islam". That is not trying to blame all muslims alike, but I do get the feeling there's many people who are more concerned with sweeping inconvenient truths under the rug than to actually address them.
Another issue is the cultural angle. Seperating culture from religion is especially hard in case of islam, but I'd put it like this: As many
people SJWankers are happy to point out, there is a lot of violent stuff in the bible and it has a lot of passages that tell readers to do some really aweful stuff to people of other religions. However this has no influence on western christian culture. Christian, contempoarary, western culture is a lot less aggressive (to the point where the pope defends Islam!).
That' not necessarily the case with islam as a religion and the many cultures in the middle east, where there's a lot of old fashioned believes and traditions that might not even be related to the Quran, but are very popular amongst muslims in certain regions. Strangely enough, it seems this is worst for 2nd (and subsequent) generations, as they fall prey to radicalization even more. I assume it's a dissonance of the cultural in-group (it est: their religious community of people with a similar migration background) and the surrounding cultural sphere of the country they live in. Add to that the fact most of the shit they know about "their own culture" is just hearsay and that might explain why they cling so much to radical ideas.
@Ntwadumela could doubtlessly elaborate on this a lot better than I ever could dream of doing,
especially since I am not too familiar with the different versions of islam, though.
And just to add a short PS: I don't intend to excuse any attack, terroristic or otherwise, I'm just questioning/exploring the circumstances that lead to these attacks. If someone is unable to deal with western culture, privileges and rights, they can fuck off right to Saudi Arabia and get their hand chopped off for wiping their ass the wrong way for all I care.
Jesus... this turned into a wall of text. Sorry for that.