An excellent statement on the subject, from Roland at
The real historical significance of nationalism consists in its imposition upon heterogeneous populations by absolutist governments. The transformation of Europe from a vast complex of interconnected private properties, across which an individual from any region could freely travel, to a collection of territorial nation-states signals an abrupt change in political association. The real historical significance is the conscious eradication of more localized and often overlapping forms of communal identities in favor of the creation of mass, territorially-defined artificial identities. I don't think it's useful to simply speak of a uniform "nationalism" throughout history without looking at the particular forces behind each instantiation.
Multicultural societies can only exist in the absence of government-owned borders and civil rights laws, which take away the safe harbors from which people may interact or not interact as they choose.

And in response to this,
Normann, I am afraid this is incorrect. The European Scandinavians will run round giving them Vitamin D, dole money, social welfare, free housing, free religious schools, and a lot more, paid for by a diminishing band of middle class sucker-whites.

You will suddenly wake up to find there are large 'no-go' areas in Oslo where even the police are scared to enter, where Sharia Law prevails, and which the Left will parade as 'vibrant testimony to how people of different cultures can really, really live together'.

I think on your way back from the US, you should visit the UK, where major areas have effectively been ethnically cleansed of whites.

You will not read the truth in the media, you must see for yourself.
more from normann at at iSteve.

...Besides, there is a difference between surviving and thriving, as those of us who believe our lying eyes are finding out now. If you are a Tamil who moves to Oslo in your 30s, you are practically guaranteed to be an injecting type-2 diabetic by your 50s, no matter what you do. Even I, with my Czech-French-Anglo-Irish mixed complexion, need as much sun as I can get. On sunny weekends I have taken to going for strolls though Oslo's immigrant neighborhoods in shorts and shirtless. I get my vitamin D and have the added bonus of letting the tent people know who decides what is proper attire on a sunny summer's day in Norway.

I'll stand corrected when the children of warrior-caste taxi and bus drivers (for example) ditch their modesty and start following my sartorial example or deign to go to ag school to learn how to farm in a subarctic climate. I don't know about you, but I'm not holding my breath.
Make no mistake, Europe remains a nationalist society. The Left thinks, for now, that social democracy provides a big enough tent for anybody in the world to populate the Nation. Their error lies in conflating the Nation with the State. When the Left realizes its error, as Ralph Nader apparently did in this interview with Pat Buchanan, Europe's multicultural experiment will take a drastic turn.