If you were promoting those things by showing them in a positive light, then that obviously wouldn’t be a good thing. By making it a negative thing, there’s a much lower risk of people thinking it’s a good idea and that your character is right. There’s a fine line between showing a character who has different ideas than you do.
You could have them arguing with someone about why they dont believe in medicine. You could explain a reason behind it- perhaps they had a bad reaction once and don’t want to risk it again. Maybe they were raised under parents who believed in everything natural and holistic and that carried over to them, and now they don’t believe in it. Their reasoning could be compounded- on the surface, they may just say “It’s for weak people!” but below that there could be legitimate fears.
There was a post somewhere recently from another writing blog that I’m trying to find, but it explained how to go about writing things from your characters that you, as the author, didn’t agree with/share the same view on. Such as a character that’s racist, when you are not, etc. If I can find it, I’ll reblog it again so just keep an eye out.
Good question and great answer! I couldn’t have said it better myself. 🙂