According to naturalism, which is a universal theory, the truth of the naturalist account itself, like every other item of knowledge, is merely one more adjustment to the environment or even epiphenomenal shedding. Therefore, the naturalist account has no more importance than any other adjustment except for some possible survival value it might have.
When do we get to add the label "true" on top of naturalism's explaining and determining factors with regard to naturalism itself? What's the criteria?
And naturalists cannot criticize belief in God, when---again---according to naturalism itself, that belief in God too is legitimately explained only by the factors specified by naturalism as all-determining: adjustment to the environment for the sake of survival, reproductive advantage, and so on.
There's simply no way for naturalism itself to break out of its own explaining and determining factors to even be considered to be true in addition to being--itself--merely the product of those factors. There's no remainder because that's what any universal reduction to determining factors gets rid of.