The Devil is the title given to the supernatural being, who, in mainstream Christianity, Islam, and some other religions, is believed to be a powerful, evil entity and the tempter of humankind. The Devil is commonly associated with heretics, infidels, and other unbelievers.

The name "Devil" derives from the Greek word diabolos, which means "slanderer" or "accuser"."devil", Encyclopædia Britannica. 2007. Encyclopædia Britannica Online. 29 June 2007 <http://www.britannica.com/eb/article-9030155>. In mainstream Christianity, God and the Devil are usually portrayed as fighting over the souls of humans, with the Devil seeking to lure people away from God and into Sheol. The Devil commands a force of lesser evil spirits, commonly known as demons. The Hebrew Bible (or Old Testament) does not assign this level of personification to the devil; there, the Adversary (Ha-satan) is a servant of God whose job it is to test humankind.

This entity is commonly referred to by a variety of names, including Abbadon, Angra Mainyu, Satan, Asmodai, Beelzebub, Lucifer, Belial, and Iblis. Many other religions have a trickster or tempter figure that is similar to the Devil. Modern conceptions of the Devil include the concept that it symbolizes humans' own lower nature or sinfulness.

People put the concept of the Devil to use in social and political conflicts, claiming that their opponents are influenced by the Devil or even willingly supporting the Devil. The Devil has also been used to explain why others hold beliefs that are considered to be false and ungodly.

Judaism

main: Satan In Judaism there is no concept of a devil like in mainstream Christianity or Islam. In Hebrew, the biblical word ha-satan (שָׂטָן) means "the adversary" or the obstacle, or even "the prosecutor" (recognizing that God is viewed as the ultimate Judge).

In the book of Job (Iyov), ha-satan is the title, not the proper name, of an angel submitted to God; he is the divine court's chief prosecutor. In Judaism ha-satan does not make evil, rather points out to God the evil inclinations and actions of humankind. In essence ha-satan has no power unless humans do evil things. After God points out Job's piety, ha-satan asks for permission to test the faith of Job. The righteous man is afflicted with loss of family, property, and later, health, but he still stays faithful to God. At the conclusion of this book God appears as a whirlwind, explaining to all that divine justice is inscrutable. In the epilogue Job's possessions are restored and he has a second family to "replace" the one that died.