In my world, Metethesi is the real physical place that non evil souls go when they die and they stay there until they are ready to move on (be reincarnated without any memories), and real people could go and visit and see the spirits there. Everybody had reason to become good people because they had proof it was a real place.

However, the god that ran that city died saving the earth from being destroyed by the debris of a falling planet, and souls couldnt be found in that city anymore. Rather than people being bad because they didnt believe in heaven, they had proof the only place their soul could go was Katameros, the underworld. This led to them doing anything evil they wanted including offering their souls as part of blood contracts because they didnt see any good outcome after death anyway.

(The world was majorly affected but eventually some order is restored so it wasnt pure evil forever, id appreciate any opinions people have on my story)