This MOD has a quite decent (maybe even great) idea as a foundation, but I feel the implementaion leaves much to be desired.
May I suggest a new setup for the reliious groups? It might help you in the long run.
So, I guess keeping Atheists as barbarians makes sence.
Then, you could go by the cultural groups thingy, and implement those as following:
christianity cultural group:
- Catholics
- Orthodox
- Protestants
Middle east of sorts cultural group
- Jews
- Shia Islam
- Sunni Islam
Eastern cultural group
- Hindu
- Buddhists
- Confucians
- Sikh
Pagan cultural group
- Egyptian pagans
- Norse pagans
- Greek pagans
- African pagans
Lutheranista, anglikans, mormons, jehowa witnesses, methodist, episcopians etc. etc. are just
branches of the Protestant christians, not religions per se. So, you shouldn't include them.
If you include lutheranists, anglikans, mormons etc. you should also include Koptes, Deists, Russian Orthodox, Greek Orthodox etc. etc. etc.
Not to mention the enormous number of branches for the eastern religions.
For todays major religious groups throughout the world, you might want to check out
This little site