And your missing Prager’s point, which is dead on, that secularism is required for Nazism and Communism. He never stated that it was the only component, or the most important component. He just stated that it was a requirement for those systems.
And that is absolutely correct.
I think you are wrong about that. You should re-read this from the Prager article:
"In fact, the emergence of communism and Nazism in an increasingly secular Europe is one of the most powerful arguments for the need for Judeo-Christian religions. Europe's two secular totalitarian systems perfectly illustrate what G.K. Chesterton predicted a hundred years ago: "When people stop believing in God, they don't believe in nothing -- they believe in anything."
So Prager is telling us that if we don't believe in God, we don't believe in anything. And by inference, this lack of belief leads us to socialism and totalitarianism. That is what he saying and that is just nonsense.