A lot of people like to claim that they know things instead of believing them.
- "What do you actually know about life, not believe, know.?" (Yahoo! Answers)
- "I don't believe -- I know." (Carl Jung, in response to a question about whether he believes God exists)
- "I don't believe, I know that He has done the miracle about which I told you" (Stephan Gechev)
- "For whatever it's worth, I don't "believe." I KNOW that psi and discarnate entities and UFO's are real based on Objective experiences." (Mr Mysterio, Reality Sandwich)
Maybe with the exception of Jung, who was doing a sort of knowing "ah, I'm beyond your plane of existence!", these statements seem to want to deny that one believes X, but instead knows X. A lot of my fellow atheists like to make this statement about science, as if belief is something one has to religious propositions while knowledge is the correct attitude towards scientific ideas. They seem to think that belief is unsubstantiated, lacks evidence or is equivalent to faith.
This is far outside the mainstream of epistemological thought. Belief, for philosophers, tends to mean that one has some kind of attitude of positive consent towards the proposition in question. Knowledge is a subset of beliefs. Everything you know, you believe. If you know that you are wearing a blue shirt, you also believe it. Just ask yourself the opposite: if you know that you are wearing a blue shirt, what on earth would it mean for you to disbelieve it?