In my setting there is a religion of giants (gaians) who believe magic/the supernatural are an affront to nature and must be exterminated by any means necessary.
For magic users this isn't to much of an issue. Simply execute anyone you believe is practicing magic, but gods/divine beings are a whole other story.
Gods in my world are the personifications of abstractions given life and form through the innate magic and thoughts and beliefs of mortals and with enough worship can affect their region.
The simplest solution to kill a god or at least suppress their power would simply be to not believe in them, but there in lies the problem, as your average gaian has a fanatical hatred of gods and seek to teach any groups they conquer to hate their gods as well which. This can in effect lead to a positive feedback loop where a god is believed in, but due to being seen as evil, it will slowly warp into becoming evil, harming their former followers, causing more people to fear and hate them and so on.
With that all being said, how could a misotheistic society "kill" gods powered by belief?
Edit: To add some more clarification to how my gods work. for the mainly affect the regions they're believed in through means like floods, droughts visions to devout followers and occasionally making physical appearances if they're powerful enough. As for what happens if they're contradictory/diverging beliefs of a god at the same time, eventually those beliefs would lead to the creation of separate gods.