Just because the Left in Europe has embraced the French (not American) notion of nationalism doesn't mean that everyone has followed suit. Marine Le Pen got about 18% of the vote, and I suspect that if one polled the French about their views on immigration a lot of Sarkozy supporters could be added to that 18%. There is profound anti-immigrant sentiment in some parts of Germany as well, and the Sarrazin book essentially makes the anti-immigrant point.

It is clear that significant portions of the nation in almost EVERY European country are opposed to immigration, even legal immigration in many cases, and massive numbers of Europeans will NEVER accept someone who is not ethnically French, German, Dutch, etc. as being "one of" them. I'm not the one deciding; I'm just stating the facts. Recent articles in The Economist have even pointed out that America is unlike European nations in this respect.

You might wish that it were otherwise, or you personally might consider that an African immigrant to Greece who gets citizenship is just as Greek as anyone else, but the vast majority of people aren't going to think that the person is "Greek", and a significant number of people (majority? minority? hard to say, depends on the country) will not accept them.