maybe god is a criminal for not doing more on this planet, and so he has excaped and is in hiding. Just like most criminals, they hide. Maybe that is why he doesn’t show himself, he is hidding from his crimes. (I am just having fun here.)
I think it is b/c we think of god as a father figure, human related or alien, instead of seeing god as nature, the cosmos, an energy or an interpretation. If those who believe, see god as nature (or cosmos or whatevs) for example then we don’t have to wonder why we don’t see “him” b/c then we do see “it.”
But the question all depends on the premise of how the idea of “god” is constructed in our minds. There are so many ways to interpret or construct god in our minds if one believes in such a notion.
maybe god is a penut butter sandwich, or not, or better yet grilled cheese. Grilled cheese sandwiches is where it’s at. 
To me it all comes down to this. Logic generally (to most people) reduces god to just desires, needs and chemicals (or even disease) in the head. But for some people who believe that god is not human, therefore is not deteced with human faculties or reason, the “posibility” of a god “may” exist in the mind for those people. But there is “NO” human proof for this, so it is kind of a way to say, “maybe.” (Kind of agnostic in a way I think.)(b/c there is no proof, the notion probably should not exist in the science classroom, but instead in litterature or philosophy etc)
I think deep down many people who say they “believe” are actually party agnostic, that is if they can see the uncertainties in everything. If people think they have it all figured out why people believe in god, that’s kosher, we’ll see if their opinions stand in 200 years from now. I think humans are detectives, not encyclopedias of the universe, we just fucken don’t know it all, and to pretend to is, I think . . . very incomplete. We can only reason, I eat penut butter sandwiches with athiests as well as muslims, I don’t care, as long as its a good bite, and ya don’t thow it in my face.