How we use language?

I was reading a chapter in the Norwegian book "Det Norske sett med nye øyne" by Gullestad (my translation: The Norwegian seen with new eyes). It got me thinking how we use language, sometimes we divide people in groups "us" and "them", and we need the "us" to determine who we are and that it is used to affirm our identities. And those that are not "us" are seen as different and less valuable than us. In "us" we can see some differences but these differences are set aside in favour of our similarities and because we need to affirm our identities and without other people similar to us we can't do that.

What was interesting to read in the book was also that those people who are not agains differences or other people like imigrants use expressions and words that push forward the stereotypes and prejudices against the imigrants (this was quite interesting to realize).