Ah, that makes more sense. I might suggest making Evil literally (whether or not people know it) the consequence of the conflict between the gods, rippling out across creation. Evil would be a force of disharmony that causes true conflict (as distinct from benign and positive apparent “conflict” between things that actually are complementary — a distinction of some importance to thinkers in this world).
Obviously, PCs are going to engage in conflict all the time, but it would give an interesting flavor to a world if standard fantasy heroics were something that people generally agreed were necessary, but also a sign that mortals live in a world permanently(?) disfigured and “wrong.”
Next thought. If you want to go with the standard D&D exclusive monolatry, in which everybody picks a god and devotes themselves to that god exclusively, this is, for once, a setting in which that actually makes sense. Because the two gods have fallen out, they are (especially Lunarus) jealous about “their” mortals. But this would be an aspect of the “wrongness” of the world - it’s how things are, but it’s not how things should be.
I would wonder if one sort of religious dispute would be about whether that wrongness is permanent, or if it is possible to restore the pre-conflict golden age, either in whole, or certain aspects of it. Classic things like prophecies of a messianic figure who will be able to win the favor of both gods and be a Sun- and Moon-cleric simultaneously.