I simply use this "world" example because everyone here is in the same cult as me: "The world is round cult." When I use it, they get it. If I were speaking to a different cult, I would use a different example.
You will note, both flat earthers and non-flat earthers have very detailed and complex reasoning for why they "believe" what they believe. But of course most members of either group have Not actually went to space to verify the conclusions for themselves.