> The universe, plot, and characters are all aggressively atheistic[1]. Meanwhile the prose is heavily infused with Christian religious language, references, and allusions.

I don't think there's any contradiction here. Atheists are often more interested in religious content than most religious people are, who just how with basics, vibes and traditions. Atheists (especially those that were raised in religious environments) are kind of morbidly fascinated with religious mythos.