It's fairly trivial to prove the earth isn't flat merely by geometry; travel in a triangle with 60 degree turns and you won't end up where you started. People knew this in ancient times way before christianity. But I should have clarified that I respect the stubborn contrarian flat-earthers more than docile consensus worshippers. Even if they are wrong. It's always better to be a retarded skeptic than a gullible believer, of the two extremes.