Christopher Hitchens, writing for Slate, talks about the "narcissism of the small difference" as Sigmund Freud called it. Hitchens then goes around the world finding groups hostile to each other who are in fact in most ways quite similar.
Protestants and Catholics in Northern Ireland, Uzbeks and Kyrgyz in Kyrgyzstan, Serbs and Croats and Bosnians in the Balkans, Pakistanis and Indians on the subcontinent are all examples he parses. It is an interesting article and worth your time.
