Sean Williams, whose Mieville-esque epic fantasy The Crooked Letter combines all the world's religions into one Darwinian package (and is available as a free download) explains how religious creation myths mirror the posthuman narrative.
Asked about writing fantasy versus space opera, Williams explains:
Creation myths tap into the same kind of issues as post-human SF, albeit sometimes turned upside-down: "Where are we going?" instead of "Where did we come from?" "What does it mean to be human or to play god?" I find these kind of questions perpetually interesting, so will probably keep coming back to them forever. The solo space opera books are certainly tapping into the same vein, perhaps more overtly than ever. This is what comes of being an atheist, perhaps: we think about these things more than most people. Obsess about them, probably.
That said, I do find that writing SF and fantasy can be very different on both a nuts-and-bolts level and in terms of other fundamental perspectives. Fantasy is more overtly about character and landscape, while good SF self-consciously uses science and the scientific method to take us places on wings made of metal, not feathers. There are crossovers, of course: the Star Wars novels felt like fantasy half the time, and I was more strict with The Crooked Letter's worldbuilding than I am with some of my SF. I like both approaches to speculative fiction. It keeps me fresh.