@Meridis
You're extrapolating a power struggle between the church and the nation that was never mentioned in the story, as far as I can recall. If there was one, the story should have mentioned it, which is exactly what I mean by "badly justified".
Also, you're forgetting the bit where the king got a whole new demon king to worry about because he was impatient. So yeah, I'm gonna go with "stupid".
Power corrupts, politically and religiously. Isekai always explores the human vs. god theme. Gods do shit and are selfish, Greek, Egyptian and Nordic are good examples.
Japanese believe in various gods and there is conflict between them as in the isekai stories.
@Sefferis: You're getting a lot of replies. Here is mine, if you still care. ^^: It's allso possible, that the church rose into its current place after the demonlord conntinued to attack the kingdom time after time for 800 years.... So then now the question is, why didn't they intervene before, if they knew of her role all those years before? Why didn't they help her in this life before? (Maybe her "best friend" is a planted spy?) Why not all the lives before?
"I can only appear before you in a mirror."
Yeah, sure. That goddess is just afraid she'll receive the bitch slap she earned herself.
Really...If that's the setup, I'd understand, if she just helps the 2nd demon lord/1st hero and tries to make him settle for extinguishing the bloodline instead of the world. How many people die every 100 years in one of those demon lord wars? Ending that bloodline is much less bloody. Poor princess or not.
This needs an isekai tag now, though as KatoShuu, said I think it's better not to have it as it's spoils stuff and it's not too relevant as this is more like a traditional medieval fantasy manga than isekai.
why are kings always so retarded in these stories? they just commit evil for the sake of evil and then get surprised when people are angry and take revenge...
It's not a matter of there being a power struggle. They said the church is an equal authority over the same population now. There doesn't need to be a power struggle, the fact that that them having equal authority over the same dominion is true makes them a political rival and bars each of them from having absolute authority. Further, why would the king from the time of the first demon lord know that this would start a continuous chain of reincarnations of the demon king? Even if we assume that the king was given all the information that the church had on the angel and her powers, then he would still have to considered that his own knight would consume the demon kings soul. More so, if you look at the actual results of the successive generations of asshole royalty and nobility, acting like this has only brought them benefits and power while commoners bear the suffering for their actions. He could know the future for the next millennium and would still do it as it has only benefited him and his decedents. They callously acted in a way that would get them what they want without paying the cost for it. My point is that it's a lack of morality or ethics on their part, not a lack of intelligence.
Sort of reminds me of the demon king plot in Live a Live, or No Life King Zen in Death March (though he actually managed to stay somewhat sane). Also:
1. How does this not happen more often? I doubt this is the only case of nobility abusing their power and corruption ensuing
2. That idiot king could have just let them retire to a villa somewhere. Nah; let the mob have her, and before she purifies the soul
3. Now the demon king and his castle have become strong enough to appear every 100 years. So Castlevania.