parochialism

I've been feeling very critical lately of the fact that many people, in this day and age, still propagate separatism based on race or religion, and honestly believe they are justified. In particular, I am disappointed by "minority" groups whose members feel that their separatism is justified, despite the damage caused by separatism on the part of other groups in society. Particularly those who actively exclude non-members. I don't feel a real need to justify my opinion and have listened to many counter-arguments, none of which are persuasive. Limiting oneself due to parochialism is wrong, regardless of the form it takes and regardless of heritage.
However, I would like to share that the least impressive argument comes in the form of "you wouldn't understand...," inevitably due to the fact that I happen not to share some point of heritage with the speaker. It's possible that indeed, I could never understand, but one of the points and advantages of living in a modern society is that we all integrate. Not only do we not put people at the back of the bus, we also don't all group ourselves voluntarily into exclusionary cliques based on race and religion. It's not natural for people of any heritage to integrate, but a good number of us have managed to see flaws in applying the logic of our ancestors to our modern situation. The rest of you should bloody grow up.