If we get our very identity, our sense of worth, from our political position, then politics is not really about, it is about US. Through our cause we are getting a self, our worth. That means we MUST despise and demonize the opposition. If we get our identity from our ethnicity or socioeconomic status, then we HAVE to feel superior to those of other classes and races. If you are profoundly proud of being an open-minded, tolerant soul, you will be extremely indignant toward people you think are bigots. If you are a very moral person, you will feel superior to people you think are licentious. And so on.