Before long, Columbanus clashed with Roman-appointed bishops, who were upset by his presence. They were “still employing the old Roman Episcopal pattern of living urbanely in capital cities and keeping close ties with those who wear crowns.” Columbanus was not impressed by them: “a man who will take no step to proclaim the Good News beyond the safety and comfort of his own elite circle is a poor excuse for a bishop.” (Cahill, p.188)

The bishops held a synod in 603, and demanded that Columbanus come in for questioning. He answered them with a sharp letter, taking the bishops to task for their worldly habits and lack of spiritual industry. He urged them to “choose to be humble and poor for Christ’s sake”.

The bishops then conspired with the Visigoth princess Brunhilda to have Columbanus deported. He made his way to Northern Italy, and there wrote letters chastising Pope Boniface IV, and later Pope Gregory.

To Columbanus, the pope was one of the brothers, a father abbot worthy of respect, by all means – but also in need, like any man, of an occasional jab in the ribs.” (Cahill, p.191) To Irish Christians, the bishop of Rome was “a distant figure whose wishes were little known and less considered.” (Cahill, p.181) They also believed that abbots and bishops should not be appointed by either church or secular authority, but in keeping with Celtic traditions, the people should elect their own leaders.

Celtic missionaries evidently traveled quite frequently with women companions, called “conhospitae”, who sometimes helped with the celebration of the Eucharist.

This practice was condemned in a sixth century letter to Irish missionaries written by Roman bishops in Gaul:

We appeal to your charity, not only to restrain these little women from staining the holy sacraments by administering them illicitly, but also not to admit to live under your roof any woman who is not your grandmother, your mother, your sister or your niece.” (Wisdom, p. 20)

In 664, sixty-seven years after the death of Columcille, the Synod of Whitby was held to resolve various conflicts between the Celtic and the Roman churches. The only professed issues were the date for celebrating Easter, and the tonsure, or haircut, of Irish monks.

Bishop Colman spoke for the Irish church regarding Easter. He said they were all

following the example of Columcille of Iona and his followers, “men beloved of God.”

Wilfred, speaking for Rome, said: “Though your fathers were holy men, do you think that a handful of people in one corner of the remotest of islands is to be preferred to the universal church of Christ, which is spread throughout the world? Even if that Columcille of yours – yes and ours too, if he belonged to Christ – was a holy man of mighty works, is he to be preferred to the most holy chief of the apostles, to whom the Lord said, “You are Peter and upon this rock I will build my church and the gates of hell shall not prevail against it, and I give to you the keys of the kingdom of heaven?” (Wisdom, p.142)

When Colman did not deny Christ’s words to Peter, and could not show an equal authority given to Columcille, the Synod ruled in favor of Rome.

Arnold Toynbee, in his Study of History, says, “It will be seen that in the contest between Rome and Ireland for the privilege of becoming the creator of the new western civilization, Rome only just succeeded in getting the upper hand.” (Columcille, p.46)

Celtic and Roman Christian leaders often operated at cross-purposes, according to historian Kenneth Clark. While Irish monks made copies all the classics they could find, “St. Gregory himself was credited with having destroyed many volumes of classical literature, lest they seduce men’s minds away from holy writ.”

Whenever Irish monks explicitly criticized the relative luxury and political involvement enjoyed by Roman Christian priests and bishops, they, in turn, would be condemned for some deviance from Roman Christian doctrine.

In 813, the Council of Tours censured these wandering Irish monks – “Hiberniae epicsopi vagantes” – for their extreme asceticism. “The ostensible reason for this censure was that in following such a strict, forbidding ideal, the Irish ascetics presented a remote, harsh picture of Christianity, which could interfere with the aim of converting the pagan populations of Europe to the religion. But the real reason the Irish were censured, so it seems, was that their asceticism sharply contrasted with the comforts and political influence enjoyed by Roman Christian clergy.” (Wandering, p.65)