Some thoughts suggested by current discussions of racism and antisemitism:
The natural outlook is that there are a variety of peoples—East Asians, Fukienese peasants, Westerners, Jews, Irishmen—that are distinct enough to possess qualities that might be good or bad. Since qualities differ, it is natural to feel more or less attracted or tied to one group or another and on occasion to feel that there are groups one would rather not have much to do with. Moderation is necessary though. As they say, we’re all human, we’re all different, we all have to get along, and there’s good and bad in all of us.
Words like “racist” and “antisemite,” at least as currently used, implicitly deny that commonsensical understanding of things by suggesting that it’s pathological to pick out a group and attribute some bad quality to it. Such words therefore push the discussion toward the destructive demand that the significance of group differences be comprehensively eradicated by force. So in most instances the words are objectionable.
It’s worth noting that both are recent inventions. I believe “antisemite” is from the 1880s or thereabouts and “racism” from the 1920s or 30s. (Neither is in the OED.) Still, the words weren’t invented to enforce ideological conformity and the power of a new ruling class, but to describe novel trends in thought that treated the conflict of races as the fundamental reality of politics.
Those trends were rooted in a denial of transcendent moral order, which resulted in a tendency to treat conflict as the basic social reality, and also in a tendency to explain all human things by reference to the physical side of life. Such trends and tendencies are quite natural if the idea of a natural harmony is rejected and the only rationally compelling reference points are taken to be human desires and fears, and the things studied by modern natural science. So the words do have a legitimate use in describing a particular kind of thought.
That kind of thought still exists among atheists who accept the reality and importance of the biological side of human life, including the reality and importance of biological differences. The problem is that modern political and moral thought in general, including the thought of the mainstream churches, is atheistic: it takes human desire and the modern natural sciences as the sole authoritative guideposts. To the extent modern thought admits the reality and significance of group differences it is therefore tempted to accept racism and antisemitism in the exact sense—the view that conflicting biological groups are the ultimate human reality.
Hence the hysterical cries of “racism” and “antisemitism” in response to any suggestion that there are group differences that matter. If you accept the existence of such differences, it is felt to be only natural that you will go on to accept something like Naziism. The two positions are felt to be equivalent, and to constitute a terrifying immediate threat. The reason is that on some fundamental level people are tempted by both. They are likely to remain so as long as reason in morals and politics is identified with a combination of hedonism and scientism.