Exorcism is an ancient religious ritual designed to drive demons out of people's bodies through prayer and the laying on of hands.
It is still practised in New Zealand today, mostly by fringe Pentecostal fundamentalist religions, but mainstream Christian religions say they do it in extreme cases.
The Catholic Church in New Zealand has used exorcism once or twice in 10 years, says spokeswoman Lyndsay Freer.
It is used very rarely and "not taken lightly because when you're grappling with the powers of evil you are dealing with a very strong force".
When someone is thought to be possessed - because they have suddenly become violent or have fallen into an unshakeable depression - a priest is nominated to perform the ritual, in which olive oil, holy water, incense and saints' medals might be used to "annoy" the evil spirits.
The Anglican Church uses a booklet published in 1976 to determine whether an exorcism is necessary.
Father Peter Williams, Archdeacon of Christchurch, says that although he has never exorcised a person, at least once a month he is asked to release demons from a place.
"I go and pray and tell anything untoward to leave. I don't know how to account for it, but it works."
Father Michael Blain, the exorcist for the Wellington Anglican diocese, has never performed an exorcism in New Zealand and does not intend to.
"I do not imagine it being any use except damaging in New Zealand ... How on earth can a prayer out of medieval England do anything? It is wrong."
But working in Africa, where it was culturally accepted practice and the medical alternatives available in the West were lacking, he has done exorcisms.
At home, he believes people who seek exorcism are usually victims of substance abuse, brain damage, family troubles, isolation, stress, sexual abuse or psychosis.
Assemblies of God pastor Les Dowie says "Deliverance" is used when someone's life has been taken over by some problem or fear. Senior members of each of the 248 assembly churches in New Zealand can release demons through prayer. He has done five this year but in past years had done as many as 100.
Dr Ivanica Vodanovich, a research fellow at the University of Auckland, says exorcism is "relatively frequent" within pentecostal fundamentalist groups, although statistics are not available.
New Zealand Skeptics spokeswoman Heather Mackay dismisses exorcism as a power game. She says it gives religions control over the faithful and provides followers with a sense of comfort and belonging.