OMFG this comment section is cringeworthy
Guys the one who made the assumption was not the priestess, it was the female mage from the adventurer group that attacked the elf village, just pay attention to this page:
https://mangadex.org/chapter/799782/19
The emperor is clearly referring to the priest's report as something that came way before the current events, which means that prior to the current event they didn't have anything against the MC.
Meaning, the priest did not foment this idea that the MC is a monster that should be killed, she merely reported to her superiors about how she was saved, and who saved her.
The entire MC is a Demon King mentality clearly came from the adventurer group, the King was guided into thiking the MC is a Demon Lord because of how similar the description the adventurer's brought of this alledged DK was to the Priest's report of an adventurer who could tame monsters. Stop pinning the blame on the priest when she literally did nothing but her job while clearly praising the adventurer who saved her.
You can even see this clearly in this page:
https://mangadex.org/chapter/799782/21
The woman in glasses is the female mage not the priest girl