While speaking as an agnostic, if pushed hard I would have to say at my core I believe in a Supreme Force. My high school Physics course taught me that in nature, matter cannot be created or destroyed.
So I extend that tenet a but further: I believe that when we die, our energy and/or our intelligence leaves the body and unifies with a massive energy field that has existed since the universe began. My belief is that this unified energy field has an intelligence of some sort.
How or what the effect this intelligence has on the physical world is beyond my grasp, but I feel that it exists.
I do not anthropomorphise this force. This Supreme Force is not human, nor possibly is it even spiritual as in the folk lore of organized religion. It just exists, possibly linking up to us with our energy fields (also known as auras) that surround us on our day-to-day existences.