The Church of Ceros is the dominant organized faith throughout much of Carthmoor and one of the most influential religious institutions in the known human world. Its teachings center upon Ceros, the Giver of the Light, whose life and deeds have passed through centuries of history, tradition, and legend.

The Faith teaches that the Light stands against the corrupting influence of Shadow and calls upon its followers to live with courage, compassion, honor, and responsibility toward others. Although its doctrine cautions against the reckless use of magic and places great importance upon resisting the temptations of Shadow, the Church does not teach that every practitioner of magic—or every member of the Elder Races—is inherently evil.

For most of the Faithful, Cerosianism is less a matter of theology than a familiar part of everyday life. Its temples mark births, marriages, deaths, holy days, and other important passages. Its priests counsel their communities, tend to those in need, and provide spiritual guidance during times of hardship.

The Church is led by a relatively simple hierarchy of Priests, High Priests, and Cardinals, supported by several specialized religious orders. Among the best known are the Guardians of the Temple, the martial Knights and Dames sworn to defend the Faith and its people, and the widely respected Sisters of Silence, whose hospitals and hospices provide healcraft, nursing, care for the dying and dead, and comfort for those left behind.

Like any institution shaped by mortals, the Church is neither wholly virtuous nor inherently corrupt. Its clergy include the compassionate and the ambitious, the tolerant and the intolerant, the humble and the powerful. Regional customs and individual interpretations of doctrine vary considerably.