The Bunun people believe that all things in the world have a spirit. Humans also have a spirit, hanitu, which is inherited from a person's father. The spirits from the father may be good or bad, and they each occupy the two shoulders of the body given by the mother. The evil spirit, mankwan hanitu, is on the left shoulder, which can make a person greedy and rude. The good spirit, mashia hanitu, is on the right shoulder and can calm a person and make the person do altruistic deeds. Each of the two "spirits" has its power to operate independently, and can only be coordinated via a different part of the person, one's "self (is-ang),” which does not belong to the mother or father.
In the early days, the Bunun people adopted Shamanism to solve personal or tribal issues. The introduction of Christianity and Western medicine has affected the functions of Shamanism. Traditional shamans helped all tribal people to pray for rain or sunshine and perform exorcism and control of epidemics, and also performed illness treatment, exorcism, removal of filth, spirit calling, searches for people, objects and love and fights against other shamans at an individual level. Shamans have prayers and religious instruments that have been handed down for generations, and they pray to the gods (dihanin) or drive away evil spirits. Shamans are not an independent social category in the traditional Bunun culture. The skills are what everyone tries to pick up in his lifetime.
The priest is responsible for presiding over religious ceremonies and activities and is also the person to maintain the social order in the ritual group. He is also the leader to begin agricultural rituals before every family starts their farming activities. The position of a priest is a life tenure. Although the position is presumed by public consensus, there is a trend leaning toward inheritance. This is because that the position of a priest requires professional knowledge, and the offspring of the priest usually has more opportunities to learn and can be easily voted as the succeeding priest after his father or grandfather. However, the position is still determined by capabilities, not by inheritance. If settlements are not formed completely in the newly cultivated areas, there will be no ritual groups. The performance of rituals is instead carried out at the family-level, and the person performing the rituals is usually the head of the family.
Christianity has been gradually incorporated into the society of the Bunun tribe since 1945. Nowadays, the Bunun people generally hold Christian beliefs and have incorporated their traditional culture into the new belief in their worshiping ceremonies. For example, the hymns used by many churches are sung by adopting the traditional Bunun phonological method.