Evil has many different definitions. In some religions, evil is defined as anything contrary to the mandates of God. In some ethical systems it is defined as taking advantage of another person for one's own benefit. Evil is generally considered to be the opposite of good. The devil is considered to be the embodiment of evil.
In the Bible in the book of Genesis, evil entered the world when the serpent tricked Adam and Eve into eating the fruit from the Tree of Knowledge of Good and Evil which had been forbidden. This event is known as the Fall, and is responsible for the suffering and imperfect nature of the world. (Not everyone takes the story literally, and even many Christians see the Genesis story as an allegory or metaphor, possibly for a fall taking place at a spiritual level.)
In Islam, evil is seen as something which must be actively opposed:
- Whoever among you sees a Munkar (offensive or evil act), then he must change it with his hand; if he is incapable, then with his tongue; if he is incapable, then with his heart; and that is the weakest faith.
Among the atheist community, as there is seen to be no universal moral law, there is thus assumed to be no such thing as evil, as good and evil are seen as just personal opinions, varying from day to day.
The fight against evil can be radical, even violent; however, on a more personal level, often the most successful tactic is admonition.
- Genesis 3:6-7