I see - I had assumed you meant fake as in fake account. I do still have some questions though:
(1) Is it not ultimately fraud to claim to know anything, given the fallibility of the human mind?
(2) Despite this, would it not be rather absurd to always have to append the disclaimer that you cannot be absolutely sure that your beliefs are true?
(I agree with you in saying that you can't really know if God exists or not - hence I prefer to call myself an agnostic, and not an atheist. Still, I wouldn't criticise atheists merely for claiming to know that God doesn't exist, because I don't expect people to append the "I don't know for sure" disclaimer to every statement they make. Unless there are further clues that they literally believe they have infallible knowledge, I'm happy to push skeptic arguments to one side.)