Death of Conchobhar

I think that the short story, The Death Of Conchobhar, was put to paper from the spoken story by someone who was not pagan, because if the person was pagan then they wouldn’t have mentioned Jesus in the story. Pagans didn’t believe in Jesus.  The problem with my theory is that a Christian person in this time wouldn’t have written this story because Jesus died for peace not to be avenged, so when Conchobhar in the end says he wants to fight to avenge Jesus that contradicts Christian ethics. At the same time as I say this the bible can be interpreted in many different ways, so I very well could be wrong. Another thing that bothers me is that as a Christian myself I have always heard in church and learned from my family that is not a sin to be vain but it is frowned upon by the general Christian public. So I feel that if a Christian person would not zoom in on the fact that the main character of the story was known for being cocky, vain, and arrogant.