) Anyway, as some of you may know I run a decidedly medievalist campaign. To introduce a variety of ideas without starting too many arguments, I have resurrected some of the older Christian heresies as organized churches - even if you don't use them whole cloth you may be able to mine them for religious ideas to inspire your own cults.First up: Celtic Christianity
In northern Europe, Pelagian or Celtic Christianity dominated the British Isles. Unlike the Roman Church, its Abbots (as opposed to its bishops) dominated the Pelagian Church as the Celts did not have many cities to have bishops. Pelagians focus on divine love and constancy and did not see Judaism as a rival. Pelagius, a 4th century British monk, is the great doctor of the Pelagian or Celtic Church.
Pelagius rejected most of Augustinian theology
The tenets of Pelagianism are:
1. Death came from man's physical nature, not sin.
2. Infants need not be baptized to be cleansed from original sin.
3. Penance and atonement, not Justifying grace, covers past sins and helps avoid future sins.
4. The determination of men, not the grace of Christ, imparts strength and will to act out divine commandments.
5. Good works are expressions of human goodwill and can come without divine grace.
6. We confess we are sinners from humility, not because it is necessarily true.
7. The saints ask for forgiveness for the sins others.
8. The saints also confess to be sinners because they are humble.
9. Children dying without baptism are not excluded from either the Kingdom of heaven and eternal life.
Pelagius wrote two major treatises, "On Nature" and "Defense of the Freedom of the Will." In these, he defends his position on sin and sinlessness, and accuses Augustine of being under the influence of Manicheanism by elevating evil to the same status as holiness and teaching pagan fatalism as if it were a Christian doctrine.
Augustine had been converted to Christianity from the religion of Manicheanism, which stressed that the spirit was God-created, while the flesh was corrupt and evil, since it had not been created directly by God. St. Pelagius argued that Augustine's doctrine that humans went to hell for doing what they could not avoid (sin) was tantamount to the Manichean belief in fatalism and predestination, and took away all of mankind's free will.
St. Pelagius and his followers saw remnants of this fatalistic belief in Augustine's teachings on the Fall of Adam, which was not a settled doctrine at the time the Augustinian/Pelagian dispute began. The Celtic Church’s view that mankind can avoid sinning, and can freely choose to obey God's commandments, stand at the core of Celtic Christian teaching.
An illustration of the Celtic Church’s views on man's "moral ability" not to sin can be found in Pelagius’ Letter to Demetrias. He was in Judea when he received a letter from the renowned Anician family. One of the aristocratic ladies who had been among his followers was writing to a number of eminent theologians for moral advice for her 14-year-old daughter, Demetrias. St. Pelagius used the letter to argue his case for morality, stressing his views of natural sanctity and man's moral capacity to choose to live a holy life.
Pelagianism is the dominant form of Christianity among the Celts. It is anathema to the Roman Church.
In my own homebrew campaign, based loosely on the old FGU Arden supplement, the Celtic Church is the preeminent form of Christianity in Powys and Thorien.