So, the Nonmen's agenda include keeping God locked up, presumably because that is the font of their remaining power? While God is not in Heaven (or wherever else) he is not in charge of creation, therefor his voice is muted, so everyone else's can be heard (i.e. exact changes)?
Is the idea about the Christ that he is Lucifer's son, who rebelled in turn, or was he some effort on the part of God to escape? I think there are some interesting things to be done with either. To keep it in a real-world parallel still, there is the offer of a second coming, of course, which seems to only make sense if he was God's son, rather than Lucifer's. Presumably, Lucifer would have learned his lesson about children, after the first.
My biggest question is probably, what are the ramifications of God's absence (and Lucifer's reign)? Is it just a transference, like all things attributed to God simply now are applied to Lucifer? How has the Church changed, what are the differences of it under Lucifer and God? Where God was perhaps only, or mostly, intercessional, Lucifer is more "hands-on," but rewards those most like himself? Therefor the Chruch is largely oppressive, rewarding those who seem dominance and lack humility and hubris? Lucifer is not omniscient, but fancies himself so. His plans have no been working out as he really wished. The more he tinkers, the more goes wrong, perhaps? Where Angels were once the dispensers of God's mercy and grace (mostly), now they are agents of Lucifer's will, attempting to force his orders, since plans are falling apart?
I guess this brings me into my next part, what is the story of Lucifer? Are we on the idea that he was an Angel, cast out of Heaven for wishing to supplant God? So, he established an Underword empire, so called Hell, and from there perhaps crafted Nonmen? In other words, Nonmen are part Angel? OK, that aside, Lucifer rebels and through means unknown, managed to switch places with God and partition Hell off from the world to keep God locked away?
Now, perhaps God finds a way to squeak out some of his will, or maybe some other Angel decides to help God, and so Christ is born. He realizes what has happened, perhaps by the guidance of that Angel, and so works to free God. Naturally, the Nonmen selfishly want God to stay locked up, since their voices are loud without His to drown them out, so they fight Christ. They win, but at huge costs. Now there is fear, because there is a prophecy of a Second Coming, and the Nonmen don't know if they have the strength to fight this again.
OK, I think I am rambling a bit now. On the artifacts, there are some things that can be sort of real-world parallels to actual Christian artifacts. Like the Shroud of Turin, pieces of the True Cross, or the Lance of Longinus. Also, artifacts from the war between God and Lucifer. Objects inflected with God's will and those with Lucifer's.