The history of the Culdees, or the tradition of Saint John

In the year 667 A.D. a debate was held in the court of the King of Northumbria. The debate centered around the adoption of a Christian tradition.
The contestants in the debate were representatives of the traditions of two apostles of Jesus Christ, St. Peter and St. John. The debaters who represented St. Peter were clerics of the Roman Catholic Church which, of course, is headquartered at the Vatican in Rome. The debaters who represented St. John were clerics of the Columban Church, headquartered at Iona.
Colman, the representative of St. John's tradition made the argument that the king should continue to observe the tradition taught by the monks of Iona because the customs observed by the Iona monks were, "taught me by my superiors, who sent me here as a bishop; and all our forefathers, men beloved of God, are known to have observed these customs. And lest anyone condemn or reject them as wrong, it is recorded that they owe their origin to the blessed evangelist Saint John, the disciple especially loved by our Lord, and all the churches over which he presided."
St. Peter's side responded by arguing that their founder had been given the keys to the kingdom of heaven by Christ, and further that the tradition of Rome held sway throughout a great part of the world. The Roman clerics also cited the argument that has since been an underlying theme of attack on the tradition of Iona. The essence of the argument is that the monks of Iona, and the Irish in general, are unsophisticated people in a remote part of the world. So, what could monks of such a remote place know about God or anything else?
The king chose to follow the tradition of St. Peter, because he feared offending the person who holds the key to the kingdom.
The value of this story isn't in showing the remarkable level of superstition of a medieval king, but rather that the Roman Catholic Church and the See of St. Peter has had a rival since the beginning of the Christian era in the tradition of St. John and the monks of Iona.
The tradition of St. John which, in the case of this training manual, is synonymous with the Culdee tradition did not appear with the arrival of Christianity. The tradition that we now call that of St. John started long before the Christian era.
Augustine of Hippo once said, "That which is known as the Christian religion existed among the ancients, and never did not exist, from the beginning of the human race until the time when Christ came in the flesh, at which time the true religion, which already existed began to be called Christianity."