If you need a primer, you can't do any better than this John C. Wright post on how his elves are different.
We are in the Dark Ages, and the darkness influences all things in society, including speculative literature. I mean the term not as an exaggeration or a metaphor: the technological products of our enlightened forefathers spring from the worldview which says science is a proper way to discover the mind of God by studying His works. Eliminating that God from one’s worldview eventually eliminates the respect for human life, free thought, and reason in law and custom which are necessary precursors to scientific endeavors, and eliminating science eliminates technology. Once the lamps go out, the darkness is everywhere, even in the little corners of society where children read books about spacerockets or elves.
The moderns have been taught to hate and loath their own country, their ancestors, their parents, and been told everything written before the current day is racist, sexist, homophobic, Islamophobic, transcismophobic, and pure evil. These nutbags think that their own standard bearers of the Progressive movement, the founders of their genre, were not Progressives like themselves.Looked at one way, every story is a Trojan Horse - only the allegiance of what's inside changes. The post-Christian fantasy stories were specifically designed to infect people's operating systems with damaging software like nihilism, Marxism, and atheism. (But I repeat myself.) The pre-post-Christian fantasies naturally and organically carried the worldview and understanding of heroism, nobility, and truth of a people who still accepted God's plan for mankind.
Every one of my stories is deeply rooted in a Christian world view - even those that clearly take place outside of the real world. As I explained to my beta-reader: I actually don't consider this most recent story all that different from the first three dragon stories. All my heroes desires revolve around God's plan. They want to serve their fellow man, protect their family, have a family, unlock the secrets of His plan through study and the collection of knowledge. Those are Christian ideals, and are therefore human ideals. Even if you take man out of this world where God explicitly exists and plonk him down in a world where other gods roam, they don't stop being men. That means they don't stop being built according to His design. People that try to remake their characters absent that critical spark of life wind up with cheap cut-outs and weak stories.
Devil's Drake might be the most nakedly spiritual, but that's baked into the very nature of the last chapter of the fighter-thief-wizard-cleric cycle. And if I'm going to write a story about a religious man fighting evil, tapping into the Christian world allows me to reach people on a more visceral level - the best fantasy is rooted in reality, and using a made-up religion would have carried the weight of a paper-mache idol.
But then, I don't hold the belief delusional belief of a John Scalzi that my writing skills or ideas are so utterly brilliant that they can overthrow the collective wisdom of 2,000 years of thought and study by the most learned men in the world, so perhaps my decision to 'borrow' cachet from Christian theology is a cheap ploy to appeal to readers. If it helps the reader understand how the world really works and brings them closer to God's plan, that's a criticism I can live with.