Patriotism, defined as the love of your country or way of life, can be a Good Thing. Nationalism, where you do bad things to foreigners, is a Bad Thing.
I know this is true because the Big Book of Magic Stuff says so. Of course I’ve never actually read the Big Book of Magic Stuff but this simply must be true. I doubt if anyone can find any examples at all of rampant genocidal nationalism in the the Big Book of Magic Stuff.