In the film "The Rite," released earlier this year, Anthony Hopkins plays the part of an American priest who travels to Italy to study at an exorcism school. The film is based on one of the Vatican's Chief Exorcists, Father Gary Thomas, who says his work brings him into daily contact with demons.

The idea that human beings can be possessed by evil spirits clashes with scientific and medical explanations of mental disturbance, but the belief persists in many Christian and other religious circles. Exorcism is widely practised in charismatic and Afro Caribbean churches and even the Church of England has official exorcists or deliverance ministers.

Joining Ernie to discuss Exorcism are the Rt Rev Graham Dow former Bishop of Carlisle; Dr Simon Dein, a Psychiatrist with an interest in the Anthropology of Religion; and the Rev Elizabeth Baxter, Executive Director of Holy Rood House Therapeutic Centre.