when it comes to Amane.... i think "right" vs "wrong" should be looked at with a little more nuance, maybe...
was killing Shidou wrong? yeah. but did Amane actually know it was wrong? maybe this is a controversial take, but i don't think she did. i think Amane knows others would see it as wrong, but that's not the same thing as knowing something is wrong.
Amane's belief system was almost entirely created by the cult (i say almost because it's clear she still, at least sometimes, has beliefs of her own that go against some of what the cult taught her). i think Amane knows what's right vs wrong when it comes to both her cult and to outsiders. but that doesn't mean she actually believes and knows what is Right vs Wrong.
if you are not taught something is wrong, and are even taught it is right... then why would you think it's wrong? right and wrong are not inherent things people believe. there are some things that may be inherently off putting, thanks to evolution (nature), but those things can be overridden by your environment (nurture).
and this isn't determined by age or intelligence. i don't think it's an insult to Amane's intelligence to say she doesn't know right from wrong. nor is it treating her like a child to say she doesn't understand this. even if she was a teenager, even if she was an adult, i would still be saying this.
she said in one of her interrogation answers that she believes what she did would be met with praise by those she respects (the cult).
What do the people you respect think about your sin?
I just followed what I've been taught.
So obviously they'll praise me and tell me that I did good.
she does not know it was wrong, because she does not know the cult is wrong.
