The purpose of my jellybean thought exercise was to show that “I don’t know” and “I don’t believe” are not mutually exclusive. Basically:

I do not believe [x] != I believe [not x]

I don’t believe in String Theory. String Theory may be correct for all I know: I am not a physicist, and my understanding of String Theory is cursory at best.

Because I do not have enough evidence to warrant belief, I cannot say I believe in String Theory. But that same lack of understanding means I must also say I don’t believe that String Theory is false.