Christianity was readily accepted into Celtic society because of similar beliefs between the two as well as the Christians’ willingness to incorporate Celtic practices into Christianity. For example, Christian sites for worship were often the same sites that had been used for the Celts’ pagan rituals.
The Celts considered the number three to be sacred, as did the Christians. The Christian concept of the Trinity, three separate forms of one God, was similar to the Celtic belief that their deities took different forms according to their functions.
The doctrine of immortality taught by the Christians was similar to the Celtic view that there was an afterlife, and the tradition of Celtic ancestor worship can be said to continue within Christianity in the worship of former saints.
Celtic images were used at Christian sites of worship and in Christian artwork. The high crosses seen throughout Ireland were probably an adaptation of symbolic stones erected by the Celts. These crosses, which are a variation of the Celtic cross, show the melding of Celtic and Christian images as the magnificent carvings include images from pagan mythology alongside images from the Bible and the lives of the saints.