It's dystopian sci-fi based on England though. The later lore is irrelevant, that's when it started turning into crap, especially around the later 2000s.
Here's the original from 1987's Rogue Trader:
""It is the 41st Millennium. For more than a hundred centuries The Emperor has sat immobile on the Golden Throne of Earth. He is the Master of Mankind by the will of the gods, and master of a million worlds by the might of his inexhaustible armies. He is a rotting carcass writhing invisibly with power from the Dark Age of Technology. He is the Carrion Lord of the vast Imperium of Man for whom a thousand souls are sacrificed every day, so that he may never truly die."
Definitely a Jesus figure. And a pretty subtly done one.
Yeah, oversold to me, sorry. Just to start with: "definitely" and "subtly done" are at odds with each other. You can't be both. Klaatu is "definitely" a Jesus analog. The Emperor... meh. It's strained, precisely because GW never really went there: fine, he's Jesus, but then what represents the Gospels? The Old Testamanet? The Emperor is only "Jesus" insofar as that's how "Jesus" looks to a 20th century disaffected nerdy atheist. Well... OK I guess?
Also... the 19th century British Empire is... kinda not at all viewed as a theocratic totalitarian autocracy consumed by cult-like worship of a dead god. Like, at all? It was a bourgeois, wealth-focused and extremely secular colonizer power driven by very worldly desires and a vaguely racist idea of How Things Should Be. And there's a lot of valuable source material for fiction there![1] And... GW didn't really do any of it, and almost none of that until much later.
[1] c.f. like 80% of Cyberpunk