The chief characteristics of the Devil at the time of the New Testament were these: (1) he was the personification of evil; (2) he did physical harm to people by attacking their bodies or possessing them; (3) he tested people, tempting them to sin in order to destroy them or recruit them in his struggle against the Lord; (4) he accused and punished sinners; (5) he was the head of a host of evil spirits, fallen angels, or demons; (6) he had assimilated most of the evil qualities of ancient destructive nature spirits or ghosts; (7) he was the ruler of this world of matter and bodies until such time as the Lord's own kingdom would come; (8) until that final time he would be in constant warfare against the good Lord; (9) he would be defeated by the good Lord at the end of the world. The concept of the Devil had been given its basic contours.
(Jeffrey Burton Russell, The Devil: Perceptions of Evil from Antiquity to Primitive Christianity [Ithaca and London: Cornell University Press, 1977], 256)
Keith Burgess-Jackson, J.D., Ph.D. 