"I do not believe that atheists want proof before believing."
No, not "proof". I just want substantial, empirical, verifiable evidence in favor of your claims. Just like I want for any other outrageous claims people make.
"They have all the proof they need, and are just rejecting God."
I see no evidence of your god or the god(s) of anyone else. If you have some, please provide it.
"Something has to exist before it can be denied."
I emphatically deny that there is a fluffy pink space bunny currently in orbit around Phobos.
Are you now going to tell me that there is a fluffy pink space bunny currently in orbit around Phobos else I could not possibly deny that there is?
"Thus the atheist has already heard about God, or he would be ignorant rather than in denial."
One cannot be "in denial" of something unless they know that something is true (or there is at least a possibility of it being true) and simply refuse to accept it.
Denying the existence of something based on complete and total lack of evidence is much different than denying it exists simply because I know it does but would rather it didn't.
One is healthy skepticism and the other is irrational.