Unintentional Altruism
I was playing Azjakuma for the fifth time to finish my Haless phase (WHAT? ENDHUVI APPEARED?!), so I've noticed that this is exactly what happens... partially.
The tearing apart IS INEVITABLE. The temples will inevitably cease to function. The released spirits spend their time devastating basically the entire continent, even in the lands that agree to coexistence. In this context, I could basically confirm that the spirit realm is literally the ultimate hell, and that the spirits are inherently evil (it will take a long time for them to calm down and for people to get used to their presence). They are literally on par with the average fey, so nonexistence would be preferable to passing into the spirit realm.
I'm the first to know that not all spirits are evil and all that, but that's because I'm literally an outside observer who can know this, while inside that world, probably no one even knows that the great temples do anything in the first place.
What does bother me is that this religion is vague at best, since it includes everyone other religions have told them not to do, as well as the oni. I could basically separate the nations from it and nothing would change; the only issue is whether they're willing to seize the power of the great spirits or banish them.
But at least the oni have a more focused understanding of what their religion means. It doesn't literally make them worse than anyone else. In theory, they have their reasons for devouring the souls of the dead, and they don't simply purge absolutely everyone. But the true purpose of it all is to dominate everyone. They don't do it out of altruism, but to become more powerful. Besides, a system that promotes acquiring power at virtually any cost doesn't exactly create a welcoming society.
So I want to see if you have other examples of people who might feel altruistic, when we know that's not the case, but that for the people there it could be interpreted as such. A shorter example, the ancient Esthil would fit this definition. (The "unreliable narrator" device worked well... Too well.)