There are things that I do affirmatively believe and am sure of, and things that I outright deny. In between the two is a broad spectrum of belief. Somewhere in that spectrum is the fact that I strongly doubt the existence of God, at least in the traditional personal sense), enough to where I’m comfortable saying that I do not believe in him.
Also somewhere in between the two are things that I might believe. Things that I could believe, but that I’m not really willing to commit to.
I started this post a long time ago, and never finished it. I might believe that there is something out there that I could call God- some sort of sentience or superconsciousness to the universe, sort of Spinoza-esque, or Pantheistic like Brahman. I could imagine that there’s something like that, and if I believed it I could be a Quaker or something, but I don’t affirmatively believe it because I don’t feel like I have a reason to, other than wishful thinking, and I don’t see what difference it makes. The universe is awesome and majestic, whether it has a consciousness or not.
Sailing to Byzantium 
Its hard to imagine that it really would matter one way or the other.
If God does exist he does not seem all that concerned with convincing us of it.
If there is a God (and I believe this with all my heart), then the truth about God and who he is makes a huge, eternal difference.