“One of the first victims of the intolerance of the early Christian Church was Celtic Christianity, which was dissolved by the Council of Whitby in 664 C.E. Celtic Christianity had developed its unique character during the Roman occupation of Britain and was heavily influenced by Druidism. According to legend, the first Christian church in this country (England) was built by the uncle of Jesus, Joseph of Arimathea, at Glastonbury in Somerset, on the present site of the medieval abbey. Joseph was a wealthy merchant who visited the tin mines of Cornwall for trading purposes. On one of these business trips it is said that Joseph brought the young Jesus, who was initiated into a Druidic college. Glastonbury had been a spiritual centre since prehistoric times and the version of Christianity introduced by Joseph and his disciples intermingled with paganism. A separate branch of the Celtic Church was established in Wales during the fifth century CE by Irish monks who had blended Eastern traditions with the native paganism of Ireland.
In addition to druidism, the Celtic Church had been influenced by Coptic Christianity. This unorthodox version of the new faith was founded by Clement of Alexandria, who had blended the teachings of Jesus with Gnosticism, Judaism and neo-Platonism. Clement founded his Coptic Church on the Secret Gospel of Mark, written by the evangelist in Alexandria following the death of Jesus. This gospel preserved the inner teachings given by Jesus to his closest disciples who had been initiated into the Christian Mysteries.
from “The Occult Conspiracy” by Michael Howard.