Einstein spent a good deal of energy in his later years striving to convince people that nationalism was the greatest evil facing the world. "Nationalism, in my opinion, is nothing more than an idealist rationalization for militarism and aggression." I think the root of the problem he saw lies in people's innate desire to feel part of a group and to form their identities around these group affiliations. (It is easy to see many evolutionary advantages to this, so I won't try to belabor its purpose or existence.) One of the smallest instances of a tribe is a family unit. "Family comes first" is considered a positive value, even though that mantra means that other, more "deserving" people might be treated as secondary. Others who are like you get added to your tribes. This is often a really good thing -- your neighbors help each other, church members show up when you go to the hospital, your fellow bridge players give you a sense of being neede
Thoughtful (and hopefully entertaining) meanderings ....