Since atheists so often parrot the above (almost as if it were an inspired part of their canon or rule of faith), I am inclined to think it is intended to be more than just a joke that atheists tell to edify each other, and that they actually think it is some kind of a nascent argument for atheism. Assuming that to be the case, I have two observations
First, atheists are playing fast and loose with their own definition of atheism here (something they like to get on others for). The fact is, and it doesn't look as glorious when it is stated accurately, atheists only lack faith in all these other gods, but Christians outright deny their existence.
Second, atheists are all Christians when it comes to rejecting 99% of the epistemologies that other infidels have set forth (rationalism, empiricism, pragmatism, mysticism, etc.); Christians just go one step further and say the remaining atheist epistemology is false as well (and the same goes for atheistic metaphysical theories, ethical theories, axiological theories, aesthetical theories, etc.)