Although Darwin was by no means an atheist, I believe that I am. (Belief and atheism twinned).
I keep coming back to it, my complete lack of belief in a God despite the fact that I also have what may be called spiritual experiences (as with the duck). How does that work?
To me it is far more wondrous to keep the hand of any sort of deity out of it–somehow adding a God makes everything less real, less beautiful and less horrifying. It takes away mystery and simplifies when complexity is awe inspiring.