Still, religious; Christian.
Not all religious folks are totalitarian or authoritarian of course. Not all authoritarians learned their trade in religious school. But there is definitely a connection. Especially but not just the Church, with its Pope. All bow to the one central authority of a God.
Stalin grew up in a proto USSR, that had earlier been dominated by very strict, paternalistic Orthodox churches; Stalin studied to be a priest, in seminary.
Hitler was a Catholic altar boy, they say. And knew Catholic antisemitism well. From the Replacement theology that said Jews killed Jesus. And that Christianity replaced Judaism.
In the novel 1984, the various authoritarian agencies are called "ministries."
Today, many churches are somewhat more liberal. But most demand obedience to a single, central god or "lord."
It's a little unusual for anyone to note the connection between authoritarianism and Christianity. But some do. And Spencer has.
Likely as you note, Dallas elitism had a role too. But parochial schools were often somewhat elitist. And elitists often centered around one religion or another. Crediting their superiority to strict training, and the asserted superiority a particular religion. In one religious school or another.