Why should we worry about a strange culture invading and possibly taking over another nation's land, the minority of whom might twist and distort their different religious beliefs to justify the eradication or displacement of the people, who've been living on the land for centuries?

It worked out okay for the American Indians, didn't it?

I'm not worried about Muslims overtaking or having more babies or whatever in Europe. As far as changing the culture, well, culture always changes and it changes slowly. In France you're less likely to see Frenchmen bowing to Allah, and more likely to see second generation Muslim immigrants to France become snooty.