Hold up: according to Google (and my mind), an agnostic is "a person who believes that nothing is known or can be known of the existence or nature of God or of anything beyond material phenomena; a person who claims neither faith nor disbelief in God." As far as I am aware, it isn't a qualifier. It's a section unto itself, like atheist or theist.
It's one of those terms where the definition is very muddied. Certainly a lot of people use the term that way. That definition comes from an incorrect definition of atheist, which is incorrectly labelled as disbelief, when it is actually lack of belief. While similar, they are distinct. Take the case of a 2 day old baby. It isn't capable of comprehending the idea of a god in order to have disbelief. You can safely say that it lacks belief in a god though.