One of my favorite book series is the "Sister Fidelma" mysteries by Peter Tremayne. The first book deals with a murder mystery that takes place at the Synod of Whiby in Northumbria. While the mystery and murder are fictionalized, the Synod of Whitby actually did take place. The purpose of this Synod was to establish if Northumbria would establish themselves as following the customs of Rome and their version of Christianity, or the customs established by the monks of Iona in Ireland, now commonly referred to as Celtic Christianity. Some key debates that occurred during this Synod included the date of Easter that would be observed, and which tonsure the monks would sport. In the end, King Oswiu decided that Northumbria would follow the rules of the Roman church. The argument could be made this led to the overthrow of Celtic Christianity in Ireland. It makes me wonder, what would the impact have been to history and religion had King Oswiu decided to follow the rules of the Celtic Church in 664, rather than the Roman church?