One constant of the atheist metanarrative is that religious explanations, which they equate with superstition (of which Christianity is a part) invariably get replaced by scientific explanations. They often cite the fact that whereas once people thought Zeus generated lightening bolts, they now have natural explanations for such phenomena and so we should expect science to replace all non-naturalistic explanations.
Now beside the fact that this is fallacious logic (an appeal to history) and that it ignores the reality that it was Christianity that displaced Zeus, not science, it is a contention that would seem to undermine the advocacy of atheism all together. If atheists truly believed this then there would be little need to advocate for atheism since the inevitable advance of science would certainly render all religious belief moot.
Of course the fact that they have been expecting this to happen for over a century may explain the anxiety of some.