[acdha]

They’re called science denier, which isn’t much different, and “flat earther” has a significantly negative connotation as well. I think the term matters less than pushing things into the appropriate context: leave religion a person choice but reinforce the secular world as following rational principles.

[robxorb]

I don't call them a science denier - which is about the most self-contradictory term anyone could come up with. Science is the process of questioning and doubting prior science. You're not "denying science" to question science.

I call them "flat-earthers", as that's something that is usefully descriptive of their views and that they themselves seem happy to be called.

That is, it's a name that doesn't also necessarily insult them, which as I see it serves no useful purpose for anyone and simply causes antagonism and less of an ability to successfully communicate.

Which, by the way, is the only working solution to disagreement.