Atheist
A person with no belief or faith in a higher being, or power.
<Atheist> It's cool you believe in god. I am an Atheist. (OBV.)

<Christian> Why don't you believe in god? Prove to me that there is no god...

<Atheist> Prove to me that there is no 12 Inch burning bear on your head wearing a Swastika, on a tightrope.

<Christian> Dick.