Portraying God in fantasy?

I write fantasy for a Christian audience, and while my books/stories aren’t always overtly Christian, God/religion/theology often work their way into the story.

So I’m curious—what are your recommendations for portraying God or Christianity in fantasy? In some ways, it feels sacrilegious or over-simplified to create a version of God for my fantasy world (as Tolkien did with his mythology in the Silmarilion—nothing against Tolkien, I just don’t feel confident doing it myself). On the other hand, simply renaming God in my fantasy world (as Lewis did) always feels flat or simplified (again, Lewis did it very well, I just can’t do it on the same level).

I’ve played with the idea of not renaming God in stories… because “god” is just the general world for “deity” in the English language… but the Triune God is so specific to Christianity that I don’t know how to capture that without using Christian terminology.

Do you think that takes readers out of the story? Should I try to remove religion altogether and just portray spiritual truths by using symbolism and types of Christ? What about established religion as part of worldbuilding—does that have to be the same as Christian religion (i.e. with crosses), or does that destroy the story? Should I come up with a totally different religion for the story (which feels idolatrous…) or try to keep the basic Christian narrative of Fall-Incarnation-Crucifixion-Resurrection-Ascension and just retell that story? Is it a turnoff to Christian readers if my characters aren’t religious (i.e. don’t pray or go to church) and God isn’t mentioned?

Sorry for the long post… I’ve been pondering this for a long time, and would be grateful for any thoughts!