I think it is you who are missing the gist of it.
Belief isnt separate or different from knowledge. Belief is a statement or position "of" knowledge. Belief means: I dont know. Belief means: I dont have enough knowledge to be certain of truth but I have reason to believe it is true.
If you know the truth of something you have no use for belief. Belief and truth are mutually exclusive.
The theist claim is: god exists. The atheist claim is: god doesnt exist. The agnostic claim is: I dont know. All three are mutually exclusive.
Penn Jillette doesnt know if god exists or not so he is agnostic. Richard Dawkins is agnostic. They both believe that it is impossible to know whether there is a God.
a. One who believes that it is impossible to know whether there is a God.
The theist and atheist claim have nothing to do with belief. On Richards scale from 1 to 7, a theist is 1 and an atheist is 7. Everything else is an agnostic.
If you are asked if god exists and your answer is yes, you are a theist. If you answer with no, you are an atheist. If you answer with I dont know, you are agnostic. As soon as you bring belief into the equation you are stating a position of knowledge saying I dont know. According to Penn and Richards line of thinking there are no atheists or theists. Everyone is agnostic.
I am a number 6. Im an agnostic but with the same lever of belief in god as I have belief in fairies or unicorns. ........Richard Dawkins
Penn Jillette and Richard Dawkins believe that it is impossible to know whether there is a God. They are mistaken. I am atheist. I know there is no god just as assuredly as I know there is no Flying Spaghetti Monster or Invisible Pink Unicorn.