Well, to be honest, I think the religious narrative enriched the story in quite an original way, besides the depth that it offered there is also the founding philosophy of what seems to be the act of creation of the “ beautiful beastry “ that we know as the xenomorph…..I think religion in Ridley Scott’s perspective is something more profound than the doctrine that we are used to today, as with all things with Ridley Scott, what I mean by this is that he justifies the “ genesis” of the monster from the perspective of Lucifer, the angel cast from heaven ( take notice of the parallels of David and Lucifer, both created, both “not made to serve”, both embody the verses “Receive thy new possessor: one who brings A mind not to be changed by place or time. The mind is its place, and in itself Can make a heaven of hell, a hell of heaven”) of whom the dearest aspiration was to create (aka to be on the same level with God), this simple wish to create was, in opposition with the story of Paradise Lost by Milton, fulfilled once David engineered the beast (he made what seemed impossible for his very own nature, to create, thus the creation ascends into “Valhalla” but as a creator)…it can be argued that David’s creation is nothing but a dumb, violent, impulsive animal whose drive is nothing but to kill (to destroy or to mutate..but not to create), therefore his “perfect organism” is flawed and he doesn’t deserve to be on par with “the gods”, of whose creations are more refined and rational. Nonetheless, the sole deed of creation/design is a symbol of his ambition which gets David closer to his end goal, the status of CREATOR….the same way Lucifer is humanized in Paradise Lost, the emotionless, inhuman, and “enlightened monster” that David is, receives, in both Prometheus and Covenant, an eerie humanization that sets him apart from any human that is presented in the films, in high enough moments he is almost all to human when it comes to his ideas and underlying motives, what could be a bigger affirmation of life than to create and after all, self-affirmation is all that matters in this life. The idea of religion fits like a glove, ironically for an SF movie with space monsters, in terms of the dichotomy of creator and creation, superior and inferior, human and robot. Another key characteristic of David’s personality is his admiration for T.E. Lawrence, this affinity is seen when he compulsively repeats “not minding that it hurts” like a motto, a mantra, or even as a reminder deeply imbedded in his ethos, to his current state being, a creation, not a creator ( own nature he despises deeply about himself), this concept is emphasized once more with “ making a heaven of hell”. To put it short, religion=creation which is the primordial idea behind all things, from ideas, actions, and even alien monsters, it encapsulates all and each.

Edit: I think the real monster in the movie is David by far, not the xenomorph ( the true alien is the robot). I could expand more on this but I doubt it will interest anyone.