In a normal political environment, there would be little need to pay attention to a new book by the far-right provocateur Jack Posobiec, who is probably best known for promoting the conspiracy theory that Democrats ran a satanic child abuse ring beneath a popular Washington pizzeria. But “Unhumans,” an anti-democratic screed that Posobiec co-wrote with the professional ghostwriter Joshua Lisec, comes with endorsements from some of the most influential people in Republican politics, including, most significantly, vice-presidential candidate JD Vance. The word “fascist” gets thrown around a lot in politics, but it’s hard to find a more apt one for...