Why do Atheists spend so much time debatng the existence of God?

[Tonus]

It makes you wonder how effective the doctrine is. Is it really having an effect on anyone's life if just as much good or evil is possible with and without it? Why isn't the word of the supreme creator and ultimate power in the universe able to effect change on a scale that would differentiate it from any other philosophy? I would expect to see a world where there was such a clear dividing line between those who profess faith and those who reject it, that there would be no doubt as to the validity of following a particular god and his/her teachings. Instead we get a world where people point to a Josef Stalin defensively, as if to say "well he was a bit worse." That might be the most depressing gap I've ever seen god squeezed into.

Not really, that is like me looking at obese people and thinking obesity is not a threat to a humans survival because their are obese people. The bottom line is, God gave us free will. As a Christian, God has spoken, very clearly. Unfortunately, man is evil and man has perverted God's word for their own benefit, selfish and evil desires. Unfortunately, this is a side consequence of free will.

I think you misunderstood my point. On one side, you have people who follow what is claimed to be the word of god. On the other side, you have people who reject god and his teachings. One would assume that the differences in behavior and results would be so great that the benefit to be gained from following god would be obvious. Yet the best you offer when the crimes of religion are noted is "atheists did really bad things, too." If they can't be differentiated, then where is the benefit from religious belief?