The idea of keeping Muslims and blacks out of the USA has some justification as expressed in this comment I saw on a blog

"The fact is that some animals are territorial, and they typically do not let other species or subpecies of animal that consume the same resources into their territory. For this reason, different species of squirrel will often fight, wildcats will fight, lions and cheetas will kill hyenas, all kinds of animals fight for survival. Evolution is competitive. Deal with it.

I am xenophobic because I want my great-great-great-great-great grandchildren to look like me and carry my genes."