I may not be on these forums much, but I enjoy playing the FfH modmods.
I am also a student of theology, and as such may be able to help with the religions idea. Please let me know if my contribution is appreciated, or not.
Sure, I was planning to do it anyway - to get some feedback.
So in general, religions work as they used in Civ 4/FfH2 (with slight differences in commerces brought to the city). Every one will provide a temple and a special building. Also, some other buildings will improve the effects of the state religion - or a specific religion. An example is cathedral - it reqires order of arches (the guild will stay) and provides extra happines from the state religion. Also some wonders will get better results if related religion is presnt/state. I might even restrict some common wonders to one or several religions.
Also, every religion will have a disciple and a priest. Not sure about high priests (might come later), but disciples apart form spreadin religions will have some extra abilities. Every religion wll have two special nits, one more combat oriented, and second one being spexcial-ops. But that is just an idea for now. Imight also add special "prophet" unit if needed
So, the religions are:
Oak Brotherhood (name might change) - polytheistic religion, worshiping nature and elemental deities. Some parallels with FoL and celtic/germanic/slavic religions of the real world
Special building: sacred grove
disciple: skald priest: volhva special units: valkyrie, rusalka (note: druids keep their fantasy archetype, will be associated with this religion but not require it)
Mytheia: mediterranean (including rome, greece, egypt, phoenicia etc) polytheism
special building: Temenos (holy precinkt, maybe a labyrynth?)
disciple: ? priest: augur special units: minotaur, satyr (I might replace one with "sacred band". Satyr is nature oriented, so I might move it to OB to replace rusalka)
Hermeticism: mystery religion, focusing on will power and otherworldly forces, but not worshiping gods
special building: well of secrets (library/mage guild type, no special effect pllaned)
disciple: initiate priest: mahi Special unit: ? (magic beasts and spirits)
Song of steel: worship of craft and spirits of the metal. No gods involved
special buildnig: clockwok tower? "steamworks"? special Forge? (not decided yet)
disciple:enginseer priest: runesmith Specal units: iron men (combat automaton), servitor (improved worker)
Dhamo: religion of equilibrium of elements and the proper way of things (east asian)
special building: cloud castle? (might use some ideas...)
disciple: monk Priest :dhamshi (elementalist?) special unit: warrior monk (maybe elementals?)
Lux perpetua: monotheistic western religion
special building: basilica
disciple: acolyte priest: priest (bishop?) specal units: paladin, angel
Cult of Chaos: religion of the rejected and oppressed, but also of dark wizards and demon-worshippers (including the old gods - it is not AV, though will have its elements. Probably more in common with OO...)
special building: pit of change (mutation chance? enhance unit abilities?)
disciple: cultist priest:zealot special units: chosen of chaos (melee unit), lunatic (?)
As you can see, it still can use some work. Please let me know what you think, and post any ideas you have.
A note: I plany to add angelic/demon civ at some point. In general idea, they will enter the game simillar way that mercurian/infernals did in FfH?orbis1, but I want to make some changes - and incorporate it into religions
And one more note: the alignments will be gone (90% sure...)
Oak Brotherhood - this is strong, and I like the loyalty to Celtic, Slavic, and Germanic religions and the reference to Farland. Do not add satyrs, but feel free to add some sort of wood wose (from Gawain and the Green Knight, wild forest dwellers, source of Tolkien's Woses) and maybe some sort of holy tree, and it's decendants, ie. Yggdrasil, white tree, gildergreen, etc. perhaps as a building or even temple.
Mytheia - This is a good idea. However, Satyrs, Fauns, Minotaurs, Centaurs, Mermaids etc are sort of natural creatures, the kind of half breeds of human and animal that could go well with a bestial civ. To get the mythic feel you could add naiads (water demigods), dryads (nature demigods), titans, cyclopes, fates, gorgons (true source is of fantastic ugliness, not snake hair), and perhaps have hero demigods who are sired by a particular elemental god or goddess of the pantheon.
Hermeticism - this is a great idea, as this is an element of many religions. As a religion of its own, however, there must be some theological element to the asceticism. Perhaps a Platonist denial of the material, changeable, false world and instead a zeal for truth, spirit, simplicity, and ascension. Your initiate idea is good here, initiates could begin, and as the unit upgrades increasing numbers of initiates are required to care for what could eventually become a blind, maybe even senseless, motionless priest who masters the magic of willpower and uses that control to communicate their needs. This could be a great synergy to a magic or a tech civ.
Song of Steel - This is a cool steampunk religion. Lore-wise it could be the element that prevents historical technological development and instead channels it into steampunk. There could be a dark side in that the priests use magical and technological knowledge to deceive the people into believing in (false) spirits or gods of metal. To that end your idea of industriously useful units is strong, to the point where this could be a civ which does not spread by missionaries but through civics, techs, and great prophets, and by building buildings. Perhaps they could have a bonus to production of specialists, both engineers and priests.
Dhamo - this religion is interesting. I would go with the elements idea completely, taking it from Oak Brotherhood. I would perhaps give the warrior priest to the Hermeticism mod (what is cooler than powerful martial artists with supernatural senses?) Since there are vast possibilities in the types and powers of elementals, you could perhaps make it such that a human mage becomes such. Thus you could begin with say an air mage (all tiers in air) and then with the religion upgrade to elemental. This elemental can then spread religion, cast spells, and fight. Perhaps even having all elementals of different spheres present in city over time can allow for building of many specific buildings (flight port, eternal spring, plasma forge, earth mine) etc. This would be a great synergy for a magical civilization.
Lux Perpetua - Instead of ripping off Christianity, perhaps you could make it a dark version. Intolerance, Crusaders, etc. Perhaps a priest (initally very weak and useless) can upgrade to a Crusader, Inquisitor, or Bishop. Crusader could in turn be come a Templar, then a Paladin and, upon martyrdom, become a Seraph. An Inquisitor could become something even more unpleasant, like a magic unit that upon death becomes a Fallen Angel, with some sort of penalty associated with it. A Bishop could upgrade to Archbishop, Cardinal, and then Pope, and upon Death become an Archangel. There could also be an angel upgrade tree, with any normal units upon death becoming an Angel. The upgrade tree could look Angel (weaker, with holy promotions) - Cherubim (just as weak, with healing promotions too) - Seraphim (stronger, with combat power on top and weapons) - Archangel (Death of Pope or Paladin, which are national units). This could be a great synergy with a militaristic civ, with the martyrdom culture and power of reborn angel units negating some of the frustrating costs of unit loss in warfare, and perhaps a crusade / jihad civic. The lore could be that the entire nation wishes to create heaven on earth, and thus will conquer and convert the world heedless of cost, as martyrdom produces Angels. Of course, any angel unit is just as strong as the unit that dies, but with more promotions and greater power against demons. All tech and upgrade costs still apply, however, and may make this religion too costly for zerg rush civs.
Cult of Chaos - this is challenging, since you have combined the religion of the oppressed with many evil elements. I think that oppression gives a population wisdom, such that they might be a force for good instead of evil. Thus I would keep the Cult of Chaos, but as the darkest religion. I do not know what the intended undead related civs are, so I would say that this religion converts any undead death into a fallen angel - demon - eidolon - archdemon, or hellhound for beast units. Thus upon the death of vampires, wights, wraiths, liches, zombies, necromancers, werewolves? etc. you recoup the effort of these costly units somewhat. Since it is evil it may be a little cheaper than Lux Aeterna, but may create a diplomatic penalty.
If you wish to add the mutation chance, you could include all human-animal hybrids as units too, such as satyrs, centaurs, minotaurs, merfolk, fauns, pigmen, etc. Perhaps they would be dependent on the livestock and aquarian resources you control, and the more you do the cheaper they are.
Finally, the religion of the oppressed. I would call it:
Hope of the Suffering: this religion believes that by unresisting service to any ruler, they will achieve true victory. The believers are pacifistic. Their units are simple missionaries, such as preachers, teachers, evangelists, apostles. Each upgrade increases the chance the unit spreads religion. Evangelists and apostles are not consumed in spreading religion, preachers are, and teachers build mission schools, the special building. Perhaps catechists and speakers could be added to build more buildings. This religion negates any unhappiness from civics. It's special civic could be pacifism, but it also will work well with slavery, caste system, etc. Their unique buildings add a strong cultural bonus to the nation. Thus a dark civ can sacrifice a powerful religion for a religion that is cheaper and lacks negatives.
Hope you like, gtg