Pelagius

 St Germanus of Auxerre in Brittany was a Celtic Christian sent to Britain in 429AD, making a further visit over a decade later. He is primarily associated with the Priory Church of St Germanus at St Germans and St Germanus church at Rame Head, both in SE Cornwall, UK. He came to challenge the teaching of a heretic, Pelagius. The Romans had recently withdrawn their troops from Britain in 410AD after 300 years of rule. There were many traumatic raids from Angles, Saxons, Picts and Irish tribes. However, it was also the beginning of the flourishing of the Celtic Christian church with missionaries flooding into Cornwall from Ireland and Wales but also Brittany. 

Pelagius was a British monk who was in theological opposition to his contemporary St Augustine of Hippo. The conflict concerned the human condition. Augustine believed in original sin which entered mankind when Adam and Eve ate the forbidden fruit in the Garden of Eden. Pelagius disagreed and believed saying that people are basically innocent at birth and only do things wrong because they choose to. However, they did have a meeting place in that both believed in God's love through Jesus' death and resurrection gave a way back to God by the gift of Grace.

St Germanus was sent to ensure the Celtic church stayed true to the doctrine of original sin.