Perhaps we should clearly define belief.
One thing that the RRS wants is to get agnostics to admit that they are atheists, that they don't believe in God. Many 'moderates' could also be described as 'not really believing'. I think a look into what we mean when we say we 'believe' could be beneficial.
With me, I always associated belief to that 'affirmative feeling'.
It's difficult to describe what this feeling is, but I think the important thing is that it was a 'feeling'. Perhaps the same kind of feeling you get from your gut intuition.
When belief is defined like this, agnostic makes the most sense as it's difficult to get an absolute feeling on there being a, or a lack of a, God. You get the "I don't really know" feeling.
However, when you get this feeling you could also call it 'toying with the idea'.
Sometimes I feel like I could fly, sometimes I get the feeling I could use the force or go Super-Saiyan... it's easier to think of myself as an atheist when I compare my 'belief' in God to these.
One good definition of belief (that Topher gave me once) was something along the lines of:
"You believe X if you would act on X."
So I might toy with the idea of being able to fly but I'd never be careless near the edge of a building/cliff. I might toy with the idea of being Super Saiyan but I'd never pick a fight where I had to rely on such powers. I might toy with the idea of there being a God, maybe even be able to have conversations with 'it', but would I rely on them to bail me out of life's problems?
Most people have "don't put the lord to the test" as part of their theology, so they're not supposed to rely on God anyway...
How would you best distinguish belief in God from non-belief?