In fantasy, world-building is considered crucial. You need a strong sense of terrain, of architecture, of locations. You need a plausible and detailed history, a few thoughts about language (or at least, ways to introduce concepts/objects of an arcane nature), and probably a cuisine.
And, nine times out of ten, you need a religion. (Actually, if there is more than one country/culture involved, you need more religions, but since most fantasy authors just stop at one, we will, too.)
You’ll need gods and goddesses.
Well, you’ll need one, at least.
How will this work? Is your deity omnipotent and omniscient? Or are they removed and limited – are they bound by the law of physics at all? Are they kind and wise, or impersonally cold and unfeeling? Do they communicate through human intermediaries, or deal directly with their creations? Where’s their “morality quotient” going to be set?
How can they be propitiated?
Often, they will respond to “offerings”, of course, but I would caution you against live animal sacrifice. Killing off protagonists and their friends willy-nilly has become de rigeur since GoT hit the public consciousness, so much so that we expect character deaths of even the most graphic nature to figure prominently now. But gratuitous (or even logical) depiction of the death of any other creature correlating to any cute or beloved earth-based animal is sailing into treacherous waters.
(Trust me on this: I killed off a horse in my first novel, and I have received more angst-ridden complaints about that than about any other single event in either that or any subsequent novels yet.)
How about prayer? Prayers are pretty unthreatening, right? Does your pantheon or singular god respond to those?
I mean, supposing you need some kind of catastrophic natural event to move the plot forward, but you have this benevolent, know-all/control-all Supreme Being(s) in place, who can be communicated with…and while you want to partially level a small city or bring down a mountain, you’d like to keep the mayhem under completely nuclear-holocaust proportions, so maybe the collective prayers of the faithful could limit the disaster?
And that is where, with the best will in the world, my internal critic just stops cold.
If I postulate a benign and omnipotent divinity who cares for all of Creation, one who can control both weather and geological movements, why would my character need to pray, and what good would it do, anyway?
I mean, that disaster didn’t come out of nowhere, did it?
That god/dess made that storm or earthquake to begin with.
That god/dess sent those people into the maelstrom, by prophecy or design.
That god/dess chose the solution: if they need the hero to survive, they could bloody well do it themselves without killing off thousands of innocent bystanders in the process.
They didn’t need that disaster at all, if they truly are a loving, all-powerful Higher Power with limitless abilities to shape every individual’s destiny.
As in fantasy, so in the real world you and I inhabit.