No. You mean "every" round earth theorist can say for sure what he meant. That's what you meant to say.
Umm... You do realize that most moon landing deniers are RE'ers, don't you?
Actually that's sort of true. You see, you should have worded that a little bit differently. Something like.
"You do realize that most moon landing deniers have actually been schooled in the round earth theory, posing as fact, don't you?"