I'd settle for it being widely seen as the ignorant anachronism that it is and their power over secular government being completely wrested.
If an elected leader from my country said that we need to curry favor with Neptune to stop a dry season I'd want them thrown out as would many others probably. But every day we have leaders around the world making decisions based on their Iron Age faith and that's seen as okay...because they're part of the same club? Out of the spirit of acceptance? Personally my acceptance is wearing thin watching these nutjobs break whatever they can. They belong in communes in the woods, not leading nuclear-armed countries.
I'm an atheist and think overt religious beliefs are ridiculous, for rational reasons.
However, religious beliefs are so common and dominant that it would never be labelled a mental illness because it clearly isn't. It would be like claiming that after you turn off the lights, every once in a while, you want to hustle up the stairs a bit more quickly because you get a weir feeling, is a mental illness, even if you rationally know you're safe.
It's a natural state that probably has (or comes from) an evolutionary advantage. It's just something we rationally should be able to get ourselves past.
“Fifty thousand years ago there were these three guys spread out across the plain and they each heard something rustling in the grass. The first one thought it was a tiger, and he ran like hell, and it was a tiger but the guy got away. The second one thought the rustling was a tiger and he ran like hell, but it was only the wind and his friends all laughed at him for being such a chickenshit. But the third guy thought it was only the wind, so he shrugged it off and the tiger had him for dinner. And the same thing happened a million times across ten thousand generations - and after a while everyone was seeing tigers in the grass even when there weren't any tigers, because even chickenshits have more kids than corpses do. And from those humble beginnings we learn to see faces in the clouds and portents in the stars, to see agency in randomness, because natural selection favours the paranoid. Even here in the 21st century we can make people more honest just by scribbling a pair of eyes on the wall with a Sharpie. Even now we are wired to believe that unseen things are watching us.”
It's if you see a differentiation between "mental illness" and "mental disorder". It makes sense that "mental illness" can be something which is detrimental to health or debilitating (like anything that gives a significantly warped and unreasonable perception of reality) and that may be non-lifelong/non-chronic, while "mental disorder/disability" is exclusively neurological differences that are lifelong/chronic and usually apparent during development (Autism, ADHD, mood & anxiety disorders, schizophrenia, etc.), imo.
It's like how "illness" can refer to a spread disease or sickness and isn't just disabilities. I see no reason to separate physical and mental illness from each other. Same with disorders. They're just illness and disorder/disability.