First - Jehovah's Witnesses have done an amazing job over the years proving that all other religions are false. It's true. Once you see that Jehovah's Witnesses are wrong, you've now reached an important point in existence - the realization that all religion is false.
Second - So now that you know all religion is false, who is "God"? It can't be Jehovah, Jesus, Allah, Odin, Zeus, Ra, etc. So, we are left with a nameless entity that has never communicated anything to mankind.
Third - Science is merely acknowledging what we observed. There is nothing that has been observed that even suggests there is a "God" other than what is man-made.