A tale of Blood and Honour
The Roman Church is part of a hierarchy that takes its orders from Rome, so the pope determines its bishops. The Roman Christian Church in Logres has one supreme churchman, the Archbishop of Carlion, a Cymric, Dubricus by name; there are also a dozen or so abbots of great houses. Churchmen are not considered noble unless they are also landlords, which is not uncommon. Many noble families have made land grants to churches or abbeys, which in turn supply knights in the usual feudal manner.
Differences from other forms of Christianity