I have gone for a variety of religions, reflected by the different factions, as well as one outcast religion. My model for this is the Roman Empire in the early days of christianity/the Dark Ages, where you had competing pagan ideologies, as well as a single powerful, up-and-coming structured religion.
The Six and One Spirits
The Imperials largely revere a pantheon of spirit-like deities who rarely take physical form, called the Six and One Spirits. They are so named for the six spirits who are aspects of community and cooperation, and the one spirit who is their adversary. The Six all have both a light and dark aspect, but the One only has a dark aspect, with no balancing force within himself.
Pakk - The Wolf Spirit - overcoming adversity through cooperation, community/War, mob violence
- Pakk is represented in images either as a trio of wolves acting in unison, or sometimes as a wolf with three heads. Pakk is the spirit of community, and represents those who solve problems through cooperative strength, resilience, and insight. She is considered fair, but when the bloodlust is upon her, She can act without reason.
Sylverbakk - The Ape Spirit- protection, law/Tyranny
- Sylverbakk is the Spirit of protection, and is represented in images as a very large simian. He represents those who put themselves in danger to protect the troop, but also those who stand as an authority above the troop. When Sylverbakk works to protect and care for the troop, he is kind and benevolent, but when he issues edicts without considering the troop, he enforces them, brutally if necessary.
Dray - The Horse Spirit - agriculture, work/Cowardice
- Dray is the essence of prosperity through hard work and dedication. When displayed in images, Dray is depicted as a large and strong horse. Dray can also be considered flighty or skittish, and when challenged, may run from a fight.
Sett - The Badger Spirit - wisdom and learning/Anger
- Sett is depicted as a small, stocky badger. He is revered by those who take great precautions, prepare for the future, and avoid confrontation. However, Sett is seen as unwelcoming, arrogant, and unkind, and when cornered, lashes out viciously, sometimes not knowing when to leave a fight.
Gyre - The Falcon Spirit - the sky, weather, vision/Aloofness, Callousness
- Gyre is depicted in images as a flying bird, far in the distance, never close. She is revered by those who wish to influence the weather, or who desire insight about the way ahead of them, but she is sometimes seen as "above the affairs of petty mortals" and out of touch. It is said "Praying to Gyre is like shouting into the wind, and just as effective."
Karion - The Vulture Spirit - death, circle of life/Ugliness
- Karion is little revered, but seen as a necessary incarnation of life. Depicted as a bent, ugly, elderly vulture, Karion is the god of death, but also of the life cycle, and the god of renewal and sustenance through death. Karion's ways are brutish and vile, and he is seen as ugly even by those who revere him.
The Gaunt - a featureless bipedal form - oppression
- The Gaunt is seldom depicted in images - it is considered ill luck to scribe an image of him, for it is said he is drawn to his own likeness. To say even his name is considered a curse. He is the god of oppression, of shackles, of cruelty, of the knife. It is said the Gaunt takes without giving. Those that revere The Gaunt are those who have lost all hope in the Six, and look instead to the One, to make a quick end of either themself or their enemies.
Worship
Cities and towns with Six and One Spirits adherents usually set up a temple structure - usually a wide pavilion with a six-sided dais in the center. On feast days, during equinoxes and solstices, and in times of great need, this dais is used to burn offerings to the Six (food, fabrics, anything combustible of value - they believe if an item is not consumed by the flame it is not accepted by the Six).
Priests of the Six and One Spirits are either Priests of the whole religion (Heirophants) or of one particular spirit (Sectates). They dress austerely, in grey or brown robes with embroidered markings of their faith.
Notes
Some Imperials follow the Orthodoxy's religion of the Twin Gods, and some even revere Troon the Uplifter (though mentioning these three in a temple to the Six and One Spirits is generally considered in remarkably poor taste).
The Orthodoxy
The prime religion of the Orthodox is called The Orthodoxy, or the Codex of The Twin Gods. Followers of this religion believe the universe is comprised of two balanced forces, wild and civilized. Their outlook eschews a good/evil paradigm, and recognizes as fact that suffering exists in all of life's aspects. The Paradox of the Twins is that one survives best when both are revered, when both ways work in tandem with one another.
Veril - god of wild places
- Veril is represented by an image of a tree, encircled by a river, which represents the sphere of nature and all within it. Veril is a provider of life-giving sustenance - meat, fruit, roots, vegetables - as well as the source of water and rich earth for planting. Veril also represents the danger of chaos, of predator/prey dichotomy, of illness and misfortune.
Cyrene - god of civilized lands
- Cyrene is represented by a tool, usually a hammer but sometimes a shovel, and represents the taming of nature to carve out civilization. Cyrene provides safety, medicine, a hearthfire, and order. Cyrene also represents the dangers of civilization - oppression, poverty, filth, and starvation.
Worship
In small towns and villages, worshippers of the Twin Gods will sometimes place a small stone sanctuary in the wilds outside of town, and a small enclosed grove within the town. In large cities, they will build a temple structure, consisting of a large encircled area, bisected. One hemisphere, representing Cyrene, is the stone temple structure, which itself encircles a much smaller garden. The other hemisphere is the Grove of Veril, which contains a small stone portico or dais within.
Priests of the Twin Gods are priests of BOTH gods, without exception, and are identified by their staff, a long, gnarled wooden staff with a small hammer or small shovel head atop it. They otherwise dress moderately.
Notes
Some in the Orthodox revere the Six and One Spirits, but very few of them revere Troon, which is considered a "human religion" to many of them.
The Shining Light of Troon
Troon the Uplifter - god of reason, trade, diplomacy, and law.
- Troon is known by many names, and is seen as the god of "good" and all that this entails. He is the Shining Light, the Uplifter, Providence, the Foundation and the Firmament, and many others. Troon's followers believe following the edicts of the church will bring them prosperity, and that if prosperity fails to find them, it is because they themselves have some flaw in their faith. The morality encoded in the Libram of Troon is ambiguous at best, and often self-contradictory, but adherents cite passages and verses from memory to justify their actions. According to the Libram, it is Troon who brings us knowledge and light, who lifts us out of the darkness, and who rewards our faith.
Troon is opposed by various unnamed and unknowable forces of darkness, called "adversaries". People who follow the Six and One or The Twins are considered followers of adversaries by those who revere Troon.
Troon is generally not depicted in images.
Worship
Worship of Troon is conducted in churches called "Spires" - these structures are almost uniformly the tallest structure in the settlement. In large cities this is sometimes accomplished by the addition of taller and taller minarets to the temple roof. Atop the tallest spire or minaret is always a glowing lantern, kept lit by the monks who serve there.
Priests of Troon follow a strict hierarchy, from the lowly monks through to the Grand Bishop. Monks dress in hooded robes, but as one progresses up the ranks the hoods disappear and are replaced by mitres, and these and the robes grow increasingly ornate.
Notes
Troon is largely revered by the Reclaimers, who eschew other forms of worship. They consider the thought that Troon worship is a "human religion" to be slander.
The Old Faith
In isolated (rural or wilderness) settlements, far removed from cities and well-travelled roads, the "Old Faith" is still practiced. This is effectively ancestor worship. there are no temples, but each household maintains a small shrine, where they pray for aid and guidance from either one or two illustrious ancestors, or the group of their ancestors as a whole.
This is largely considered heresy by the three main faiths, (though the use of the phrase "By the ancestors" has long since passed into popular parlance and is considered commonplace, even when removed from ancestor worship).