The Reason I'm not worried
Here's the thing. If you are scared of fundamental islamists taking over your country and enforcing their private version of sharia upon you there really is nothing you can do.
Yes there is, a society doesn't have to be tolerant - but this is unthinkable because being less tolerant would be considered a step backwards. And there should only be progress is the mantra - a society can only become more tolerant, more open, there is no space in the box for the thought that there'd be negative effects for being more open and tolerant. This is the right path, the path forward. You can never be enough open and tolerant.
Look at what the romans did to christians back in the day. fed them to the lions. Look at what the norse did to christians, chopped their heads off.
If such extreme measures didn't matter then what will? Nothing, right? Right.
The roman empire adopted christianity, it's a powerful meme when population density is increasing and an empire grows bigger and bigger.
But it has negative effects as well. Certain things do not prosper within the christian meme (for example individual creativity). Look at medieval times - the whole of Europe was united under the christian banner which made it possible to withstand an islamic invasion.
Religion is a meme. You cannot stop it by taking lives. You need to offer up a better alternative.
Yes, you can stop a meme by force. Look at various sects which got busted by forceful intervention. Look at Catharism, well they can't tell you their story because they all lost their tongue.
Now look at where extreme islamist is spreading and it isn't any nice places where they've got their shit in order. The best alternative to fighting this fundamental dystopia that a lot of people like to label "Islam" is together your shit together and build a better alternative. Which really shouldn't be that hard if you look at public hanging videos from Afghanistan.
The bigger problem is that power hungry white men sieze on this opportunity to create pseudo-fascist right wing parties all over europe. Selling the false idea that muslim immigrants are the root of all evil.
Power hungry white men - Aha. Well now that this is clear - on what fertile grounds are they planting their seeds? On the tabula rase generation, the nil people - the people who are just clay with a nice ego which you can manipulate. They eat up everything because they were trained to be molded. They were selected for that. One day they are open and tolerant, the next day they are fascist or communist or whatever totalitarism is your fancy - we will see how the "reasonable" people will fare when times get harsher...
Funnily enough that's the subject which Nolan(the Batman dude) dealt with in his recent Batman movies.