Okay, so, a recently closed thread almost had an interesting discussion buried in it, but because it was related to emotionally charged topics, it wasn’t ever gonna happen there.
So let’s try it here!
What the heck is magic!?
Sufficiently advanced technology?
Reality by fiat? ("As I Will So Mote It Be!")
Psionics surrounded by swords & castles instead of lasers and rockets?
What it probably shouldn't be is defined by exclusion. "Supernatural" or "Something Science Can't Explain" - magic is antecedent to the idea of the scientifically explainable.
So I'm going to go with the middle one. Magic is the manifestation of conscious will - belief, faith, confidence, longing, love, hate, justice, right, anger, etc - directly or indirectly.
Magic gets /called/ "magic" when it's seen as out of the ordinary, but, magic can be ordinary, too.
Yeah, that means getting up in the morning is magic, at least when a conscious person does it.

(Sure seems like it some mornings.)
Now, it is my opinion that IRL religious/mythological miracles are magic. Full stop.
Odin and his brothers breathing life and thought into the first people? Magic.
Burning bush acting as a conduit for god’s voice? Magic.
I genuinely cannot fathom what definition of magic precludes these things from being magic, as such, so I’m curious what others think on this topic.
There's a distinction between Thaumaturgy - magic that accomplishes something practical, like healing the sick, or demonstrable, like levitation, or otherwise serves the purposes of the magician - and Theurgy - magic that serves the purposes of God (or the Gods, or some other higher power or purpose), maybe not exactly entirely selfless, but beyond just the magician. A Ritual like the Eucharist is Theurgy. A 'miracle,' evoked by a person, is generally Thaumaturgy.
IRL, non-believers could consider Thaumaturgy magic tricks (and charlatanism), and Theurgy legitimate religious rites & rituals - or they could opine that it's all malarkey.
Now, we have to avoid arguing about religion here, so we should try to keep examples from RL faiths to a minimum and not dig into the theology that underpins them too much, but
Hopefully that wasn't too deep.
Now, what is magic to you?
The answer I gave above is kinda the M:tA/The Secret/Ars-Magicka answer, in essence just about /everything/ people do, and the world they live in
because they live in it is magic. Which is, really, just begging the question or something, I guess. Because the real answer to the question is what gets called out as magic.
In M:tA, for instance, post-modern beliefs shape the world (in itself, an en masse act of Magick) into the edge-of-global-environmental-catastrophe/rife-with-injustice/war-torn/compliant-with-scientific-laws/hell-on-earth/World of Darkness that it calls "The Consensus" or "Consensual Reality." Other beliefs, less pervasive but even more deeply held, create room for fringe science, Vampires, Werewolves, Ghosts, Miracles, etc... and find expression outside physical reality in other planes of existence, collectively The Umbra (shadow).
So while Magick (The Metaphysic of Magick: belief determines reality) is responsible for essentially everything, it's the 'minority report' of belief that gets labeled magic or supernatural. Even though some of those beliefs and the practices associated with them might be entirely internally consistent and repeatable, they're not broadly accepted enough to stand along side science and mundane experience as part of "Reality" (nature) so they're beyond it: supernatural.
Ironically, just because somethings supernatural doesn't mean it's all powerful or unlimited, it just follows different laws.
I post this in the context of dnd, because I am not satisfied with divine magic in dnd.
I think there is space here for a very interesting discussion of what magic is, what separates mortal magic vs that of the divine vs the magic of lesser spirits and powers, etc.
In D&D, magic is nothing like Theurgy nor the Metaphysic of Magick, nor any RL belief. Nor is it simply non-scientific. D&D magic is, essentially, super-power grenades. You pull the pin, and you gain a super power for a while. You get a new shipment of grenades each morning. There may not be much rhyme or reason to it (though there's certainly some rhyme, or at least alliteration, here or there), but it's perfectly consistent, dependable, and repeatable. A Scientist given some cooperative magic-users should hypothetically be able to derive exactly what's going on, or at least, describe and predict what magic is capable of in exacting detail.
In the 1e DMG, spellcasting is described as pulling energy from the positive material plane, maintaining some sort of conservation principle by exchanging it with the material components of the spells (or if none, the air exhaled by the mage as he speaks the spell), and shaping it through the symbols impressed upon his brain by the process of memorization, whipping out said symbols in the process. Yeah. Helpful, that.
In FR, it seems like "The Weave" is the explanation for magic of all kinds. That fits, because all kinds of magic work the same: spells, slots, the exact same spells on many different casters' lists, whether they're arcane, divine, or even using ki to toss elements or shadow around.
I can see all sorts of things potentially dis-satisfying about that, but what, in particular, is the issue you have with divine magic in D&D?