Earlier quoted context omitted.
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…
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 ne…
40k is not a satire of "Jesus," its a satire of Jesus-obsessed materialist Britain. How can you say that 19th century Britain wasn't obsessed with worshipping a dead god? They worshipped Jesus, put him into every part of everyday life, said that if you didnt worship him you'd end up in hell being tortured forever, etc etc...
There doesn't need to be an entire 1:1 translation of the Bible into 40k for it to be a satire. A carrion-God Emperor of (white) Mankind who is "apparently" watching out for all of us, at all times, and gives us manifest destiny to rule all other races? That's the modern political Euro conception of Jesus, ensconced the same way into an Imperial state.
The British Empire was extremely secular? You might want to brush up on your history. The COE (Britain's State religion) was not friendly to other religions inside the Empire. Especially at home. The British Empire was a devout place. You couldn't own property as a non-Anglican Christian until 1846! And they said their Jesus-God was responsible for everything, everywhere, at all times.
Outside of Egypt and Ethiopia, Christianity exists in Africa why exactly? India they found it was too difficult to break their faith, so it wasn't worth the bother when they could extract resources anyways. But Africa is heavily Christian for no reason other than British missions.
Bourgeois & wealth-focused is exactly how the Imperium is set up. They don't care about anything other than control and wealth being sent back to Terra. That's part of the satire too.