Bangkok Atheist maintains that a negative proposition such as “God does not exist” cannot be proven. As such, atheists do not know that God does not exist, they “just believe” this to be the case.
Unfortunately, no one has been able to prove the positive proposition that a God exists, so religious people must have faith that a deity resides somewhere.
Nonetheless, since the atheist also has to rely on his own faith that a deity is illusionary, then the most logical course of action for the non-religious would seem to be agnosticism.
After all, if one does not know that God does not exist, then why be an atheist?