I would think that the agnostic presumption of "existence of god is unknowable" lacks neutrality as much as the presumption "god exists" or "god does not exist". It is stating that it is "unknowable". Maybe the "knowing" part is a matter of time. Much the way Hume explains away some of the miracles. The Indian that has never been in the cold climate and seen the water turn to ice. I would take a soft agnostic stand, "existence of god is not known at this time".