Richard Norman is a humanist philosopher. He is interviewed by Nigel Warburton in the Virtual Philosopher blog. Norman is asked why he rejects the idea that God exists. His reply is a paragon of clarity:
I believe that the onus is on those who believe in the existence of a god to provide reasons for that belief. (This is a point which the philosopher Antony Flew has well made.) I can’t prove that there is no god, but in the absence of good reasons for believing that a god exists, I live my life without belief in a god. In particular, the success of scientific explanations of the natural world makes religious explanations redundant. It’s in that sense that there is a tension between science and religion. The two are not logically incompatible, but the more we succeed in discovering well-founded scientific explanations of the origins of the cosmos, the origins of living species, and so on, the more the explanations in terms of a divine creator become redundant. They add nothing.
I could not hope to put it better myself. This is exactly my position.
Geoff Coupe's Blog 
Leave a comment