My one sentence answer:

--------------------------------------------------------------------------
Because God does NOT exist as the personification we give him/her.

--------------------------------------------------------------------------


Remember, God (or by whatever name you call the force/energy responsible for all of creation) is beyond comprehension by our relatively small and puny intellects. In order to relate to such an incomprehensible/unimaginable energy we create personifications such as God(s), angels, ect. All these concepts, whether you realize it or not, are of one and the same.

By taking the personifications too far and personally we create human fallacies which are incompatible with logic and science.