I have this friend, N, that has recently started believing things very out of the ordinary. He said that he's been getting into paganism and studying runes and candles. I told him that was very interesting, it sounded like a fun time and a good hobby to have. N let me know that it wasn't just a hobby, but that it had a function and purpose, a sort of witchcraft.
I come from an academic background; it doesn't seem healthy to me to actually believe and try to practice witchcraft, not because it might be real, but because of the mental health associations with it. So I told my concerns to N but he brushed them off, saying that people have the right to believe in what they want. I respect that, but I do not want N to fall into delusion. I let him know, as respectful as I could, that believing in witchcraft does not make it real and that it wasn't healthy to believe otherwise. He got really bothered when I told him he should talk to his therapist about this stuff. N has a history of mental health issues and was in a deeply abusive relationship for a few years which cause him a lot of grief. I was accused of being rude and trying to impose my beliefs. His last message to me was him asking me to stop and that anyone has a right to believe what they want.
I cherish N a lot as a friend, I do not wish them any harm. I respect that anyone has a right to believe what they want, but I really don't think this is healthy for my friend. Is there any way I can help him? Is the best way forward to just stop and let him be?
If you believe in the scientific method, then you know that trying to coerce a change of opinion is a bad thing. Just let your friend be, if they ask you any questions respond with your honest opinion, but don't try to force them to reevaluate their beliefs if they don't want to have that conversation. Imagine how peeved you would be if the tables were reversed and they kept nagging you to trade in your smartphone for a scrying stone.