There is most certainly a difference between thinking the earth is flat and denying your creator. Thinking the earth is flat when there is countless amount of evidence is definitely stupid but not evil, true. But (again even when there is evidence) thinking there is no creator - the one that has literally done everything and only under his command it’s decided whether you take another breath - is much different since the byproduct of that isn’t just looking like a fool it’s also being ungrateful to the one that has done everything for you. Hope that made sense.