If boiling water scalded my hand, I
know that it will do so again. I don't
believe it. I lived it and I therefore know it.
Part of knowing is experiential.
However things which I do not experience personally, which are filtered through the media, or which I have no first hand knowledge, I will more than likely use the word believe.
From Ruby the Adventures of a Galactic Gumshoe, (a very smart play for the mind) they pose an interesting theory: "The media creates reality."
Other than personal experience, you almost have no choice but to believe what is fed to you via some form of the media. You can choose to trust the media and other people's opinions, but it would be hard to truly know for yourself, unless you live it up and close personally.
At some point, some of us make up our minds and use the word 'know' to replace the word 'believe' because we think we think that we've gathered enough evidence as proof of personal knowledge.
So what evidence do I have to live through to go from "I think there is no God." to "I know that there is (or is not) a God."?
I don't have the answers for myself yet, but I do know (heheheh
) that I've not had that key experience that has convinced me one way or another.