Here is where the rubber meets the road: To claim that there is no God, without reservation, leaves the claimant with the burden of proof to shoulder, not the theist. For the atheist to purport definitively that there is no God would mean that he has all-knowledge. If he hasn't omnipotence, he or she is speaking from a faith and belief position, no matter how much they recoil from the thought.
The "definitively" isn't there very often, at least in the internet community I run with. It's just that evidence doesn't support claims of gods.