Very astute observation. Plenty of conservatives have opined that liberalism is a pseudo-religion. And it is. But that means it is embraced by people who want or need a religion. Those of us who have no space in our heads for religion of any kind are no more likely to choose liberalism than conservatism. For us, it boils down to who makes the best argument, or to what we have observed. I think Ayn Rand makes a better argument than Karl Marx, and my observations are that the more largess the government distributes, the lazier and more self-indulgent the recipients become. I have seen it with my own eyes. Thus I am conservative.
Atheism allows for no ultimate objective source of individual sovereignty.
The only kind of individual sovereignty consistent with atheism is the subjective kind, which makes it no different, ultimately, from any form of liberalism.
The other pseudo-religion is environmentalism. Heretics are figuratively burned at the stake for denying or even being skeptical about AGW.