Setting: In this world (i.e. the one in which you’re reading a WBSE post), intelligent life turns out to be fairly common throughout the universe, just it tends to blow itself up somehow before it can colonize a major section of the Universe and find other intelligence, since discovering FTL is extremely difficult. Somewhere across the galaxy from Earth, there is a species that not only discovered FTL, but also discovered it fairly early into their process of space colonization, which lead them to become the dominant species in the galaxy. When they explore the stars, they frequently find the remains of information-age or even space-age civilizations that have long since died of famine or war, be it in the form of remnants of spaceports and stations that are still around after thousands of years or deep-space probes that have been running on Bussard ramjets, eternally waiting for new commands from long-dead masters as their infallible engineering keeps them alive.
There turns out to be a small but nonzero number of other civilizations alive: the dominant species, humanity, and a few others that have largely been confined to only interplanetary colonization. Wherever the dominant species goes, they find no trace of anyone else, humanity or otherwise, having invented FTL at any time.
Issue: The dominant species’ Empire has a state religion, revolving around the Empress, an actual deity-like being who, due to technology long since lost, has become functionally immortal in a perpetual vegetative state, retaining awareness and the power to effect “magic” (see Arthur C. Clarke’s quote) on the world. This state religion is enforced by a government militia group; in fact, it’s enforced to the point that worshiping other gods or even denying the Empress’s goddesshood is considered blasphemy of the highest order and is usually punishable by death.
This creates an issue, because I’d like to be able to have a world where this dominant species and the other non-FTL species can tolerate each other without constant crusades/revolutions. As it currently stands, the most logical result of this setting is that the dominant species either “re-educates” other species on the holiness of their Empress or just straight-up destroys them, which the other species can’t really stop since this dominant species has some of the most advanced technology and by far the largest armies in the galaxy. So, despite their fanatical worship of their God-Empress, why does the dominant species allow other species (who are all technologically and militarily inferior) to worship other gods, or no gods at all, and not constantly ignite crusades against the “unenlightened”?
The goal: a world where other species are allowed to worship whoever they want, if they worship anyone, and aren’t at risk of being annihilated by the Empire for their heresy. It’s fine if native Imperial citizens don’t like other species and incite speciesism, so long as it doesn’t end with a crusade on another species.
The assumptions that I’m making are
- that excluding humanity, there are four surviving space-faring civilizations that are all comparable in technology to us on Earth, and that the Empire directly controls around five million stars while other species only hold sovereignty over their home star; and
- that if the Empire waged war on another one of the surviving species, the Empire would, without question, win the war on account of their warp drives and super-advanced weaponry that can sterilize a planet in a matter of hours.