@Eorl,
Not really a mess ! Very simplistically philosophy points to two positions.
Either "reality is out there" and "things have existence" independent of observers, or "reality is a construction" based on species specific and culture specific needs. In the first case, "knowledge is about "objective facts", and in the second, it is about social (paradigmatic) agreement as to "what works" or "what is useful".
The problem with "agnostics" is that they are stuck with type 1 (naive realism) without any "objective evidence" for a deity. I f they moved to type 2 they would take the position that "objectivity" is a myth, and that "evidence" lies in the eye of the beholder.
IMO the second position is superior because it transcends, and encompasses the first in that it allows for observer-observed interaction in accordance with developments in physics (post Heisenberg).