Negative theology? Nope. I'm not an atheist but a pragmatic agnostic. There's no proof that a god exists any more than it doesn't. But to be able to define a god that would exist, we would need to know if it exists or not in the first place. We can't just burn the steps for the fun of it or to appear as having more knowledge than everybody, which would be an outright lie in this specific case. Nobody possesses that knowledge. If a god was to exist, maybe it would sleep, maybe it would eat, maybe it would even shit... but we don't even know if it exists or not, so how can we say it does this or doesn't do that? Existentialists don't burn steps.
Referring first to your brief question, negative theology refers to the idea that we can say nothing about God in concrete terms. For example, we can neither say that God is wise nor that He is stupid because those are terms invented and used by human languages. Shouldn't that stance alone indicate what you're trying to emphasize about the limits of human knowledge on God?
And if you'll be so kind as to let me indulge in a brief rant to defend my rejection of divine anthropomorphism, the choice to believe in the existence of a God is indeed a leap of faith that will remain unreciprocated. I should have clarified further, but if one is to approach the concept of God from a Western perspective, we encounter the idea of the Creator God. By the very nature of the things around us (Viruses, DNA, blackholes, stars), we're often faced with the reality that the physical elements capable of affecting us most aren't anthropomorphic.
By that logic, then, it seems overly arrogant to cast a being which created everything in the cosmos within the frame of a human form; why should this deity assume all these anthropomorphic qualities other than to placate our own human egotism?
Hell, if I had to choose a form for God, it'd be as a virus. Sure, everyone knows of HIV and Ebola, but few also realize, for instance, that endogenous retroviruses allow mammalian fetuses to implant into the wombs of their mothers without being obliterated by the immune system. Likewise, most of the planet's oxygen comes from marine bacteria, which obtained their photosynthetic capabilities from a case of horizontal gene transfer conferred by bacteriophages. Both the propagation of this species and the generation of their life-stuff both seem Godly to me.
And while existentialists indeed don't burn steps, they also affirm that their decisions are their truth since they're the ones that have to live with those decisions. To that end, the merger of my discipline with some basal level of spirituality is how I can articulate myself on the subject. Needless to say, my 'truth' isn't nor should it be your 'truth' (unless I was forming a cult) due to its inherently subjective nature.