ExJW here also. I am not an atheist because I can not prove a universal Neg. It would take faith to say you are an atheist. I am an Agnostic. I can not prove there is or is not a god but since I have seen no evidence of one, I tend to lean that there is not.
An impersonal God that exist solely as a power outside of our physical universe would be pretty hard to disprove. However, a personal God with a personality like that described in the bible is easy to disprove as there our many contradictions to his personality found in nature. To get around this JWs fall back on "Satan did it" and "Imperfection though."