Sun-Faith
The tales of the founding of Meridian and the Carja people are rife with imagery of the Sun, given divine and life-giving traits. Araman, who led the group to split from the Nora, discovered the Leaves in a ruin, directed by a shaft of sunlight. The Meridian Spire seemed to reach up to touch the sun, directing the weary travelers to the mesa which would become Meridian. The Carja have taken such divine solar intervention to show that the Sun is a deity worthy of worship. Its desires are interpreted and executed by the Sun-King. Some Carja even believe this divine right makes the Sun-King infallible, an embodiment of the sun itself, leading them to split and become the Carja in Shadow when Avad slew Jiran.
Sun-Faith is an organized religion — it includes temples, an order of Sun-Priests, scheduled daily rituals, branded ornamentation, and even judicial powers stemming from its political integration. Like any belief with governmental support, not all Sun-Priests are able to resist the temptations of power. Canonically, it is not clear if the organization is rotten to the core, or if Aloy just happened to find the few bad apples.