I took a cue from some of the other OSR blogs and Sandbox makers out there and left a lot of stuff in my setting pretty fast and loose, hoping the players would fill in the blanks. For one, it's less work for me and players often come up with wacky and unpredictable concepts. Part of this experiment is saying yes instead of no to player creativity, so I left the gods deliberately vague. What I decided on was that the world is influenced collectively by what are called the Powers. They're a huge group of entities of varying levels of influence and power over the mortal world. Some might be gods, others demons, powerful spirits, elementals, ancient heroes, otherwordly monsters beyond human comprehension, etc. They can all grant a measure of their power to favored followers who have dedicated themselves to the service of their patron. I also liked the idea of a more cultish angle to these churches so I think there will probably only be a few 'churches' and the rest are hidden mystery cults and enclaves of creepy robe wearing weirdos. What I really hope happens is that the players interested in that stuff will create their own secretive sects with complicated handshakes for their characters. There are plenty of interesting real world examples to look at for inspiration and of course there's always the movies, which are full of awesome creepo cults. I worked on a couple to serve as examples and came up with some interesting names that the players can take and flesh out too.
'The King is the Land. He carries it upon his brow, and he is honor bound to unite all good men at arms to defend the Kingdom; under one banner.'
Brian Conlee, now called Brian the Blessed
At the right hand of the first King of Moray stood a man of unshakeable courage and great cunning, known then as Brian Conlee. So great was his loyalty to his liege lord that even after victory was won and the King granted him many lands and titles, he gave over all his wealth and power, remaining instead by his lord's side until the end of his days. It was said that so long as Brian Conlee stood by his side, the King would remain victorious and no harm could come to him. When he died he was buried in what would later become the royal crypts, watching ever over the Kingdom he served. Centuries later his story inspired a small but fervent cloister of holy warriors who continue to serve the Kingdom in his name to this day. They most often act as militant chaplains and keep alive the deeds of their patron through oral tradition and eschew the trappings of temporal wealth and power, freeing themselves instead to serve worthy lords in emulation of their beloved Saint. Very rarely, one might strike out instead seeking to serve the Kingdom as an errant, performing worthy deeds to serve the Land; that which the King represents. The only outward symbol they wear to identify themselves is a simple iron chain; it's weight reminding them of their Oath and duty to serve.
Domains: Healing, Protection, Strength, War
Servants of Brian the Blessed must swear an Oath to serve ever their liege Lord or the Land or be Cursed as an Oathbreaker. They may not in word or deed harm the object of their Oath and must endeavor always to act in it's best interest.
And some names. Some of them I took from real world mythological sources since they fit in well with my concept.
Horned Serpent of Eld
Domains: Blood, Darkness, Domination, Trickery
Domains: Chaos, Death, Destruction, Fire
Domains: Animal (Bull), Fertility, Strength, Sun
Domains: Fertility, Health, Sun, Wisdom
Domains: Madness, Destruction, Darkness, Psychopomp
Pytun, God of the Grapes
Domains: Charm, Madness, Chaos, Fertility
Lord of Beasts
Domains: Animal, Earth, Health, Sky
Orphus the Intercessor
Domains: Justice, Order, Protection, War
Artos, god of the Wild Hunt
Domains: Animal, Blood, Destruction, Strength
The Demon of the Burning Pit
Domains: Chaos, Darkness, Destruction, Fire
Sarth of the Shadows
Domains: Darkness, Luck, Psychopomp, Trickery
Lord of the Golden Crossroad
Domains: Earth, Psychopomp, Sun, Wisdom
Domains: Chaos, Destruction, Sky, Weather
Namarre the Even Handed
Domains: Death, Moon, Order, Spirit
Children of the Black Circle
Domains: Death, Darkness, Spirit, Trickery
The White Bear
Domains: Animal, Earth, Strength, Wisdom
The Blind Watcher
Domains: Blood, Darkness, Earth, Psychopomp