I think in the game's situation, changing someone's beliefs is actually on you. The devs even said that based on the choices you make, your companions will either like it or not. They will also choose to either stay with you or leave but at the end of the day it will all depend on the choices you make in the game. That also means that just because someone is "evil", it doesn't mean they will stay that way. You might be able to change them based on your choices.
That suggests you frame your actions to accommodate the companion rather than the companion changing.
