I did this for personal use but figured someone might also get some use out of it.
Very much a work in progress. I haven't tested a lot of this. So this is for people who like to play around with their game. Don't expect too much out of it, but please tell me if something seems really unfitting for the situation.
The game has a set of generic 'Good Cleric' 'Neutral Cleric' and 'Evil Cleric' player dialogues where they mention some generic divinity. The tag 'Good Cleric' gets replaced with 'Cleric of Ilmater' (for example) dynamically when the dialogue loads.
Using the epic power of find and replace I have written some more specific dialogue for those tags. I also added a little more in other places (which will show up even if you're not running a [whatever] cleric, so don't keep this installed on non-cleric runs) where I thought it was appropriate.

Lathander:
-No dialogue with companions is changed yet
-I tried not to reword any lines that have narrator or character voiceover, thought it's possible I did by mistake
-Stuff about the sun, the dawn and so on. Most of the generic good guy good cleric dialogue focuses on 'the light' anyway so didn't require a lot of changing.
-I reworded some of the dialogues with minor undead in act 3 so you can roleplay mercy-killing them as a good thing. Also with a certain boss if you turn up without Astarion
-Some dialogues dealing with the mad monk, such as declining his offer, are nicer.

I might do more god options, if new tools make picking through the strings easier.
I am not gonna do every god cause there's like a billion of them, and some people might have different ideas on what 'x' god might want than I do.
Someone I know who runs a cleric of Mystra has expressed interest in working on a version for Mystra so that might happen at some point possibly.

If you want to make your own, or edit mine, it's as easy as unpacking this mod and writing your own things in it.
How to Install
Recommended that you install with BG3 Mod Manager. A guide to BG3MM installation of mods can be found here.

Mod fixer may be required.
Hard requirement: either Game Text Compatibility Base Files OR Overexplained Companion Interactions.
This is because the game needs a mod with the entire .loca as a dependency or individual text strings refuse to be overridden for whatever reason.


Uninstalling should be the same process in reverse, should be good to uninstall anytime.

Credits and Thanks
Thanks to the creators of BG3 text parser tool.