Might it help to talk with him about Flat Earthers?
Do "flat earthers" exist?
Apparently 7% of Brazilians are flat earthers.
physicsworld.com/a/fighting-flat-earth-theory/
If we don't share "flat earthers'" belief that the earth is flat, due to the evidence of our own eyes/ experience/scientific knowledge, does that therefore mean we do not want or believe flat earthers (or 7% of Brazilians) to exist?
Do I personally have to go along with flat earthers' wacky ideas because they truly, truly believe it and always have believed it for as long as they can remember and there are conferences and videos and 'scientific' papers which posit their theories etc? Even if they are delightful, wouldn't hurt a fly types, I can respectfully and perfectly pleasantly disagree with them, yes?
I mean I would generally say live and let live, I don't share your views but enjoy your flat earthing, no skin off my nose, have fun etc.
Except
I don't want you teaching flat earthism to 7 year olds in schools in their Space topic; I don't see any value in Flat Earther Story Time at the library; I actually think being a Flat earther should probably disqualify you from a job at NASA or the Civil Aviation Authority.
I also don't think the BBC should prioritise Flat Earthers' views over those of Real Earthers, I wouldn't expect them to write almost weekly puff pieces about you or only mention your flat earth beliefs when you are the victim but never the perpetrator of a crime nor would I expect them to have you on for 'balance' any time they are talking about Space.
I definitely don't want you having the particular ear of government. I would be highly suspicious of politicians who would say that "flat earths are Earth" and a Prime minister who would be prepared to say 99.9% of the time the Earth is spherical except for when it is disc shaped. 🤯
If you are a flat earther, I reserve the right to privately think that you are foolish or deluded or that you have fundamentally misunderstood the Bible or you are just doing it to get attention or to provoke a reaction. I think that there must be something in it for you but literally nothing that benefits me.
Still, other than that, once again, live and let live, knock yourself out flat earthing, no skin off my nose etc. Exist away!
If, on the other hand, I was to find that flat earthers were part of a movement predicated on removing women's rights, invading women's spaces, demolishing safeguarding, casting the language I use to describe reality as 'hate speech' and mutilating and sterilising predominantly gay and autistic kids, well, that would be a whole different matter....