I'd heavily argue for Hussie not being religious, of if he is, not letting that influence his work. Sure, HS has heavy gnostic themes, but it tears down pretty much everything else that is a running theme in other religiously inspired works. There is no 'God', no big good, no one is really immortal, no one person is really omnipotent, the only being one could argue is a god like figure is a destructive giant moron who everyone hates and the kids become gods themselves, ruling over their own (1)
Universe, something that wouldn’t sit well with anyone that is really into their religion, as humans becoming gods is something that is always decried, even in works that aren’t religious, but especially in those that are. (2)
I mean, there’s a thousand different ways to interpret religion and religious things. Skaia IS a God-like figure, specifically Abraxas-like, and the Denizens also act similarly, or at least as Demi-Gods. The Genesis Frog, too, is linked to the concept of a Pantheism, where the God that is the Genesis Frog embodies the Universe itself- And he is praised as such by the Carapaces.
Hussie may not be religious, but when I see the things he’s done with religious themes, I don’t really see him tearing things down, rather I find he’s done a lot of research to talk about those topics, and is approaching them to express something deeply personal. Whatever he believes in, though, I have no idea.