In a forum i was on previously, there were a bunch of blockes (English and Australian) who were convinced that French people were inherently bad or inferior people: dirty, corrupt, mean etc… No argument could convince them otherwise. Needless to say, I found it rather strange at first, especially from the Brits who are our neighbors and allies and all that. I thought they were pulling my leg. But no, it was just a form of casual racism like any other.
One day i joked that learning English was easy because half the words were French. (To be precise, since I researched this issue back then, 41% of the 10,000 most common English words are of French origin.)
A big fat runcus started. Those blockes fought tooth and nail against the evidence I provided.
Based on this experience i am now wondering if some forms of casual racism are not a device to HIDE a common origin, a cultural borrowing, an ancient link or debt from one people to another.
Take antisemitism. @Jeruba rightly pointed out that Christians appropriated the entirity of the Jewish scriptures and made it their own. Christian antisemitism could be a way to hide this “borrowing” under the carpet.
Another example is the strength of anti-black racism in the US (which seems to me stronger than elsewhere): couldn’t that be a way to hide the debt (at the least moral) that the nation owes to slaves from Africa, who helped build America?
There’s also the European attitude to Arabs. It’s undeniable that European civilization owes much to the Arabs.