True enough, no true scientist is ever absolutely sure they're right about anything. (That's one reason Jesuits are quite often scientist.) But there are a fair number of people who are, and sometimes they get hyperactive trying to "dictate what others do and should believe".

"Yes, I'm right! - and you are wrong!" Sometimes it's about believing in God, sometimes it's about it being shamefully crazy to believe in God. Perhaps more often it's the latter variety on the Mudcat, but who knows? In fact, who cares?