I'm not asking for advice about charactes, plot etc. but rather about religious themes, morality and how these things should (and shouldn't) be portrayed, so that my book can have good Christian morals.
I'm working on a fantasy novel that puts a lot of emphasis on philosophical and religious themes. I noticed that in a lot of novels and other forms of fiction (movies, manga etc) that I know of, these things aren't portrayed or are portrayed poorly. Characters follow vague ideas of good and evil, without going into detail how or why things are good and evil in the first place (this applies especially to works set in different universes than ours). Some works that portray such themes often just scratch the surface and create questions without even suggesting answers. Religion is skipped or portrayed on a very shallow level, not as something that affects the entire worldview and all actions of the religious. That's what I want to avoid.
I also don't want to just write a parable. I want to give a lot of attention and quality to characters, setting, worldbuilding etc but that's not the topic of this thread.
What I'm asking is what should I do and what should I avoid doing if I want to portray a fictional world in accordance with Christian truth?
Some info about the setting and some things I'm unsure about (in pink):
Setting is late-medieval-like
Most of the plot happens in a part of the world that doesn't know about the Christianity-equivalent religion
The world and everything in it is created by the one true good God, there are no other (real) gods
There are angels and demons (fallen angels) (this part of the setting isn't expanded at all so far)
There was a Fall of man, similarly to our world (also not expanded yet/not too important to the story)
Timeline wise, most of the plot happens before the Christ-equivalent's incarnation and earthly life - there is something like the God's Chosen People but they are geographically far away, rather insignificant and unrelated to the main plot
In the location where most of the plot takes place, there is a dominant pagan religion
This location is ruled by an empire (consisting of vassal kingdoms), which is very focused on the religion. The emperor is the central authority and is believed to be chosen by the deities of this religion. Religious devotion is one of the most important duties of the citizens.
These deities, as mentioned before, aren't gods/God - but they do actually exist
<and they aren't demons either. They are humans ascended to a higher level of consciousness/existence/nature. This "ascension" only happened because demons/the devil-equivalent gave them the power to do this (for their own foul ends - so that people would be led astray and into sin by these deities [who believed they were doing something good]).
<They received physical immortality/invincible bodies and could perform false miracles, which they used
along with their other skills to sway masses of people to serve, believe and worship them
I'm not sure about the humans achieving godlike powers thing, I mean I would like to include it as it's pretty important to the story so I'm trying to solve this by attributing their apparent powers to demonic sorcery
they are eventually defeated, and their earthly bodies destroyed
<but they are banished to a different dimension, where they still have consciousness and can control themselves, however they can no longer directly influence humans
their existence does not depend on people's belief in them, but the more people worship them the more power they receive
the main plot plays out several hundred years after these events
they are starting to manifest/influence the world again for reasons I don't want to spoil
many characters in the story live according to Christian virtues, despite not knowing the Christianity-equivalent religion or the Old-Testament-Faith religion; this is not their own achievement but rather the result of all men having God's law written on their hearts/conscience and being unknowingly guided by God for a greater purpose
<there is magic in the setting, however it is sorcery, it comes from demons, it always has negative side effects; it's also rare and limited - not important to the worldbuilding and story, except for the deities
there is no "good magic", however there are miracles performed by God through holy men/prophets who know him (rare)
There's much more to the story and stuff, but these are the things I'm most concerned about and I don't want to reveal too much so people don't steal my unique 100% OC ideas :) . I appreciate all advice, if you have any questions about the setting related to the issue of the thread then I'll answer.