The church which existed in parts of the British Isles before the mission of Augustine (597) and which maintained its independence for some time in competition with the Anglo-Roman Church. Little is known of the introduction of Christianity into Britain, but by the fourth century it was sufficiently organized to send representatives to the Synod of Arles (314) and the(359). The Pelagian heresy spread to the , and Germanus of Auxerre visited England to try to combat it (429). Monasticism came to the Celts by way of Gaul, illustrating further the contacts the church had with the Continent.
This was changed by the Saxon invasions about 450, which isolated thefrom continental life and resulted in the extermination of Christianity in England. It survived only in remote areas of the British Isles. When Augustine's mission reestablished contacts with Rome, the Celtic Christians argued with the Romans over such matters as the calculation of the date of Easter and variants of tonsure. These differences were settled at the * (663/4) resulting in a victory for the Roman practices.
The Celtic Church under the leadership of missionaries such as Ninian* (c.400) and Patrick* (c.440-61) featured the monastery under the abbot, rather than the bishop's diocese, as the unit of ecclesiastical organization. Each monastery served a single tribe. The abbot was a tribal leader, and the bishop was a subordinate official in the monastery whose duties were wholly spiritual. The leaders and heroes of this movement equaled the ascetic extremes of the early founders of monasticism. A typical act of self-mortification involved standing for long periods of time immersed to the head in an icy stream. Another characteristic of the Celtic monastic life was an emphasis on missionary work. The highest service to Christ was lifelong exile to evangelize foreign lands. Thus the Celts sent out men like Columbanus* (585-615), who preached in France, Switzerland, and N Italy. The Celts also encouraged scholarship and had a rich artistic tradition, particularly in sculpture and the illumination of manuscripts.
N.K. Chadwick (ed.), Studies in the Early British Church (1958); idem, The Age of the Saints in the Early Celtic Church (1961); L. Gougaud, Christianity in Celtic Lands (ET 1932).