One problem with promoting atheism as an ideology is definitions; it used to be a popular comeback among atheists to say that "atheism is simply lack of belief in God," but this presupposes a definition of God that Theists have never been able to provide . How do you know you don't believe in God unless you know what it is you're supposed to be not believing in? Suppose your cat was God and you just didn't know it because you never cared for getting your definitions straight?

One way out of this problem is to come up with an alternative definition of atheist, which is what Victor Stenger does in "The New Atheism," defining an atheist as a " materialist.who thinks that science is the best way humanity has yet come up with for understanding the world. "

The problem? It's flat out wrong. Nietzsche was the one who said "God is dead" to begin with, so if Nietzsche isn't an atheist then no one is. But he wasn't a materialist and he didn't think that science was "the best way humanity has yet come up with for understanding the world."
In fact, Nietzsche said that materialism was "one of the best refuted ideas ever put forth," and he wasn't too fond of Dawrins theory of evolution either, instead promoting his own version of evolution based on the Will to Power.

Bertrand Russell wasn't a materialist, neither was Ludwig Wittgenstein, neither are contemporary physicists.

Materialism isn't an escape from metaphysics, its literally just another metaphysical system, enable to accept it I would have to have some coherent idea of "matter" and think that that idea has something to do with reality. Not believing in metaphysics would mean being a Nominalist like me, Wittgenstein and Russell.