For Americans here, I take atheist in the traditional usage, that is to mean one that believes that there is no God and differentiates it from an agnostic being one who neither believes there is a God nor disbelieves that there is not
There is a rather cheesy claim made sometimes by atheists, I believe it was also made by a popular celebrity atheist, who, like a tale told by a fool, is full of sound and fury but signifies little. It takes the form that the burden of proof lies with the believer or put it another way, that the atheist holds the most logical position
The claim that the burden of proof is on those that say God exists is exactly that; just a claim. We must ask is it a valid one? Well, there are many things we accept as true without being able to prove them (Where proof means 3rd person proof)An example of such is consciousness; you cannot prove to me you are conscious and I cannot prove to you that I am, we do however accept that we are conscious because we experience it. Similarly, I can not prove to you that I know God exist or that I experience him but my experience of him is of the same kind as my experience of being conscious and similarly unmistakable.
So the atheist is faced with a logical dilemma; either they must accept that their belief that they are conscious is no more valid that the believers faith in God,
OR
They must admit that they are logically inconsistent