Mark 1:23

An outburst from a man in the congregation interrupted the service. He was under the influence of a demonic spirit. The Jews spoke of demonic spirits as evil or unclean spirits. Mark used the terms "demon" and "unclean spirit" interchangeably. This is his first reference to demonic influence on human beings. [Note: For additional information on demonic influence, see William M. Alexander, Demonic Possession in the New Testament: Its Relations Historical, Medical, and Theological; Merrill F. Unger, Biblical Demonology: A Study of the Spiritual Forces Behind the Present World Unrest, ch. 6; and idem., Demons in the World Today, ch. 6.] The man cried out with a strong emotional shriek (Gr. anekraxen).

"Neither the New Testament, nor even Rabbinic literature, conveys the idea of permanent demonic indwelling, to which the later term ’possession’ owes its origin." [Note: Edersheim, 1:481.]