There seems to be a large percentage of Bible people (not that there's anything wrong with that) on this board. Particularly amongst the Americans. I thought a poll might clear up our assumptions.
My personal belief is that a rational person would have to be Agnostic. And that the other two are missguided. But I expect to be in the minority here.
examples to help you decide your vote;
Religious person is Gnostic = to have knowledge of (God)
Undecided person is Agnostic = Lack of knowledge (needs proof)
Non religious person is an Atheist = To believe that there is no GOD.