Unification of Celtic Christianity with Rome

We have noted in earlier posts how the Gothic Arian church developed in fifth and sixth centuries and how the Pope in Rome gained power in Spain in the Third Council of Toledo 589. Expansion of Islam during the seventh century wiped out the remains of North African Gothic Christianity.

Standard Western tonsure
Fra Angelico wikimedia

Celtic Christianity was changed more gently with the arrival of the Gregorian missionaries to Britain in early 7th century when Islam was spreading and soon threatening Christianity in Spanish peninsula. It suffered greatly from the Vikings who pillaged Britain, Scotland and also Ireland for over two centuries but Thor was unable to unseat Christ from His throne in the British Isles.

Symbolically speaking we may say that the sign that Celtic or Insular Christianity (insula, island) had merged with Latin Church was when the monks tonsure changed to standard style and the date of Easter was calculated according to the Roman system. All in all, the process took some four hundred years and we may suspect that many other local traditions persisted among the Celts at this time.


Unification during centuries

Saxon connections with the greater Latin West led to papal preferment and brought the Celtic-speaking peoples into closer contact with the orthodoxy of the councils.

The customs and traditions particular to Insular Christianity became a matter of dispute, especially the matter of the proper calculation of Easter. Synods were held in Ireland, Gaul, and England (e.g. the Synod of Whitby) but a degree of variation continued in Britain after the Ionan church accepted the Roman date.

The Easter question was settled at various times in different places. The following dates are from A. W. Haddan and W. Stubbs (ed.), Councils and Ecclesiastical Documents Relating to Great Britain and Ireland, 3 vols (Oxford, 1869-78), I, 112-3:
South Ireland, 626-8
North Ireland, 692
Northumbria (converted by Celtic missions), 664
East Devon and Somerset, the Celts under Wessex, 705
the Picts, 710
Iona, 716-8
Strathclyde, 721
North Wales, 768
South Wales, 777
Cornwall held out the longest of any, perhaps even, in parts, to the time of Bishop Aedwulf of Crediton (909)

Read the entire article in wikipedia