There's a difference between patriotism and nationalism. Patriotism is love for one's country, which is what many soldiers and those football players in New England have. Nationalism is the belief that one's country deserves (and is) stronger and better than other nations. If one is talking Nazism, it was the giant surge of nationalism - not patriotism - that brought the German National Socialist Party to its peak. I doubt many Germans were carried up in the thought that they loved their country; I think more so, they were determined to prove to the rest of Europe that they were simply better. I mean, weren't they the Aryan race of superhumans?
I think everyone deserves to have a sense of patriotism to their country, whether it's their nation of birth or nation of citizenship. And love for one's own country is a different matter than for another person. I could love America just as hassel loves America, and just as FlightFreak loves Belgium (and it's Clijsters). It's hard not to question why anyone would love America, but I'd ask you the same thing: why would anyone love their country? I think, in all fairness, it really comes down to living the same life as ours. If you were born in America, you may come to dislike it, but in the deepest sense, your roots are from America, you grew up in America, most (if not, all) your friends and family are American. You may not have the greatest love for America the government, but I'm sure if you were American, you'd have a deep, abiding respect for America the country.
"I like refried beans. That's why I want to try fried beans, because maybe they're just as good, and we're just wasting time." - Mitch Hedberg (1968-2005)
"Football is about if you want to run and fight for each other, if you really want to play that killer ball." - Robin van Persie, Arsenal FC