Tbh, with how grey the morality in that world is, we can't yet make the call that Gwen is evil, since there's arguments that could be seen her as trying to introduce change in situation where people are repressed, think similarly to the repression of totalitarian/extremely religious states have. Like you say, people have to suppress sides of them that are pretty innocent, to the point of hurting themselves and their families. Also the fact that Athia's faith thinks women that have bigger tits are inherently bad, because Athia is herself flat and Isha had bigger tits. We are only getting snippets about these things, but Athia and her followers are not really just the good guys, considering how Isha and her followers has been persecuted. Yes Isha went behind Athia's back and fucked with her husband, but that itself doesn't necessarily justify everything that happened to Isha after it.