Doesn't you being so against God prove he exists?
This is a misunderstanding. It's not the god we're "against". It's the people who claim to follow one, and who do many bad or unwise things in the name of their god.
- The followers, not the god, are violating the constitution (in the U.S.)
- The followers, not the god, are persecuting minorities.
- The followers, not the god, are writing legislation forcing their "morality", and Creationism, on everyone else.
- The followers, not the god, are cheerfully marching the U.S. into the Dark Ages II.
It's the people whom atheists have to stand up to, not their invisible friend. We'd be having this same conversation if millions of Spiderman fans were doing similar things. Atheists frequently address theists' claims because it's a foundation to the reason why they continue with the above infractions.
Contentions with a group of imaginative people is not an admission that their imaginary constructions are real.