Over millions of years, humans have developed in an environment where there was just enough food for one’s own group. Any other group encountered in the savanna posed a mortal threat and had to be destroyed. These evolutionary traits of aggression and tribalism can’t be wiped out by a few generations of centrally heated life. That explains why xenophobia is still so widespread in our society. The whole world is full of conflicts between groups with different faiths. Since time immemorial the “peace of God” has been imposed on others by fire and sword. That’s unlikely to change soon.