Pelagius was introduced in Chapter I in the context of the monastic movement, and mentioned in Chapter II as the author of a profession offaith. Here we shall examine his doctrines in the wider context of Christian dogma and establish him as a part of a broader activity. We shall then consider the evidence for the continuity of Pelagianism in Britain and Ireland and attempt to show its influence on the character of the common Celtic Church.

The Pelagian movement

Pelagianism is sometimes thought ofas a one-man heresy, but it is now clear that Pelagius himself belonged to a wider movement. Despite the fact that his name is given to the doctrine, it is not completely certain that he was the instigator. Other participants included Rufinus the Syrian, Julian of Aeclanum (an Italian bishop) and Coelestius, who was possibly a compatriot of Pelagius. It should also be recalled that John Cassian, the leader of the ‘semi-Pelagians’, did not follow at some later date, but was contemporary with the main Pelagian movement.

For our purposes, it might be useful to regard the Pelagians as a broad group, embracing the semi-Pelagians on the left (if you will), Pelagius himself in the centre, and the hard-liner Coelestius on the right. While modern theologians may object to this re-classification of semi-Pelagians and Pelagians, it may claim some historical validity. Throughout the history of Christianity, theological polemicists frequently resorted to tarring their opponents with the brush of a heresy that was similar, but not identical, to the doctrine under attack. Throughout the fifth century it was convenient to lump together Pelagians and semi-Pelagians alike as ‘enemies of grace’. This held especially true of Prosper of Aquitaine, the most vigorous champion of Augustinianism after Augustine himself, and a figure closely concerned with suppressing Pelagianism in any form in Britain and Ireland. In Contra Collatorem (’Against Cassian’) Prosper repeatedly accused Cassian of stirring up the ashes of a dead doctrine, or attempting to snatch victory from the jaws of defeat.Although Prosper occasionally acknowledged differences between Cassian and the Pelagians, he took greater pleasure in pointing out their similarities. While differences between ‘pure Pelagians’ and semi-Pelagians doubtless persisted throughout the period of the common Celtic Church and even afterwards, the two groups formed a loosely compatible spectrum of belief and practice that differentiated early Celtic Christianity from Christianity in other regions.