. . . it's not about race. It's about ideology.
If every inhabitant of a liberal democracy believes in liberal democracy, then it doesn't matter what creed or colour they are. If, on the other hand, some of them believe in Sharia and the Caliphate (and believe, too, that slaughtering the attendees of ladies' night at the Tiger Tiger discotheque is a good way of bringing that about), the numbers start to matter.