Violence causes problems that will have to be dealt with later, but sometimes its necessary to deal with problem that is too awful to let be. If you want to prevent violence you need to prevent the situation where its necessary.
imo there is a line where flexible morals is okay and where its not and its not on same place for everything. Ultimately its about will it make things better or worse for everyone.
I also dont think anyone is inherently good or evil but everyone has tendency towards something. The tendency comes from genetics, environment and random chance. Its up to them if they want to go with it or not and if they end up doing bad things and dont want to stop then they should be considered evil until they stop and repent. Though they can still pretend to repent so if threat they represent is big enough, you need to also consider what the risks are if they lie and get away.
In avatar, (major spoiler)
spoiler
aang lucked out and had the choice of having it both ways by just taking away ozais power. Without that option I think he would have had to just kill the guy or watch him destroy everything. In that situation, in my opinion, the destruction would have been partially aangs fault too since he could have stopped it. Otherwise you might as well blame anyone defending themselves from ozai for killing fire nation’s soldiers.
What makes this so difficult question is also that everyone has their own set of morals they live by. One also kind of needs to define what good and evil is, because there definitely is evil at least.
While I wont push anyone towards any religiousness, there are some good points in some holy texts. If there werent, i dont think civilization living by those religions wouldnt have lasted very long. Unfortunately they are still words written by men and thus corrupted by shitty people, like that one part in bible about “you shouldnt rape kids” that got turned into something that was interpreted as anti homosexual. Religion has always been meant to “control” or guide people, but it isnt always malicious. Though getting the “core” message from some religion still relies on persons sense of morality since you need to know what to keep and what to discard.
So maybe ultimately being good is about honestly wanting and trying to be good and being willing to adapt and change towards it. It doesnt matter if you dont definitely know what “good” is, you can “construct” it from what others think is good. Also, its critical you dont lie to yourself about anything, that is surefire way to lose your way. Educating yourself, being capable of media criticality and watching and reading many kinds of stories also helps.
there aren’t many places where you can discuss politics or at least try to find comfort in seeing others think somewhat same way. No wonder its all concentrating here. But there definitely should be a lot more non-politics content.