I do not believe there is a single member of this forum who does not believe, somewhere in a part of their heart and soul, that God exists. Including you.
You really shouldn't project your own personal beliefs onto other people. It's presumptuous, to say the least. How would you react if someone said to you, "I believe that, deep down, no Christian, including you, really believes in their god"? I think you would find it to be patently ridiculous, at the very least, because they're presuming to say that they know you better than you know yourself. Yet that is exactly what you're saying about the atheists here - that you know them better than they know themselves, at least as far as "god-belief" goes.
There is only one person you can make statements about regarding what they believe, and that's you. To say that about anyone else is an insidious form of self-deception. What makes you think your god has actually made himself known to the atheists on this forum, or ever will? That's why it's self-deception, because you're deceiving yourself with something you believe to be true, but cannot possibly know is true.