The word devil began as the Greek for slanderer
The oldest religions had no Devil at all. Egyptian and Mesopotamian gods could help or harm on a whim, and evil was simply part of how nature worked. The idea of a single cosmic enemy of goodness appears to begin with Zarathustra around 600 BC, and it has been argued over ever since.
Our word descends through Old English dēofol and the Latin diabolus from the Greek diábolos, meaning slanderer. The historian Jeffrey Burton Russell sorts the many versions of the figure into four types: an evil principle independent of God, a dark aspect of God himself, a created being that turned bad, and a symbol of human wickedness. Across traditions the figure goes by many names, including Satan, Lucifer, Mephistopheles and Iblis, and the Oxford English Dictionary even records a softer use, as in calling someone a poor devil.
Early belief systems lacked any unified concept of evil. In Egypt the gods were morally mixed and bound by cosmic order, so wrongdoing meant breaking that harmony, not serving a rival lord. Zarathustra changed the picture by insisting that evil is not part of ultimate reality but a separate principle: Ahura Mazda freely chooses good, Angra Mainyu freely chooses evil. This first known dualistic system went on to influence Judaism, Christianity, Manichaeism and Islam.
Judaism after the exile absorbed some of that dualism, but belief in an all-powerful God ruled out two equal forces. Christianity wrestled with the tension, borrowing from Plato the notion of a craftsman god working with stubborn matter. Neoplatonists described evil as an absence of goodness, and Christian thinkers such as John of Damascus built on this to portray the Devil as a fallen angel: created good, then corrupted by turning away from God.
The strictest dualism returned with Mani, a Parthian prophet of the third century AD in the Sasanian Empire. His teaching of Two Principles and Three Moments held that light and darkness were once apart, are now mixed after darkness attacked, and will one day be separated again. Scholar Yvonne Bonnetain sums up the Devil as a mythic explanation, a personified power standing behind death, disease and everything hostile to people.
Source: Devil
