I think I get you. Not a religion in the sense of being comparable with, say, Buddhism, but more like an avid interest? Like when we say someone plays golf 'religiously' as in sticking with it and being serious about it?
A lot of atheists are not avid at all, so you don't hear much from them, you could call them 'apatheists'. I suppose you usually find this avidity in what many of us call 'deconverts', atheists who used to be sincere religious theists. Often we have researched our own religion and found we weren't satisfied with it, but we retain our interest in religion, the nature of belief, ethics, and so on. It wouldn't be far off the mark to say I've made a religion of rational empiricism or postpostivism or whatever you want to call it in the sense that the topics fascinate me enough that they take up a good chunk of my internet and reading time.
You bring up an interesting point about supernatural deities, and it's why I define atheism as lack of belief in supernatural deities. A person could decide to worship something known to exist without wittingly ascribing any supernatural power to it. Arguably the philosophy of communism became an object of worship for many people. I've known what I call an 'uncommtted deist' who worships whatever caused the universe but doesn't make any claims about what that is, not even claiming it's a conscious being: if it was quantum fluctuations, that's what he worships, in gratitude for making it possible for us to exist.
Now if someone started the First Church of Quantum Fluctuations which reveres what they think is the natural process behind the Big Expansion, that would be an atheistic religion...as long as they don't believe the quantum fluctuations want or think anything. There's already an atheistic religion called Raellianism that worships aliens. I think they're irrational, but since they don't believe in any supernatural deities, I have to put them on the atheist side, not the theist side, much as I'd rather not be associated with them in any way.
Which brings us to SF. It isn't outside the realm of possibility that a being or beings with greater knowledge than us and technology unfathomable to us might seem god-like in comparison to humans, and might be worshipped by humans who didn't comprehend what they really were (like those Egyptian aliens from Stargate). For various reasons I don't really think it is probable that there are critters like that out there, but it's not impossible in a huge universe with billions of galaxies, each with billions of stars and planets.
