Evil, in a general sense, is the opposite or absence of good. It can be an extremely broad concept, though in everyday usage is often used more narrowly to denote profound wickedness. It is generally seen as taking multiple possible forms, such as the form of personal moral evil commonly associated with the word, or impersonal natural evil (as in the case of natural disasters or illnesses), and in religious thought, the form of the demonic or supernatural/eternal.
Evil can denote profound immorality , but typically not without some basis in the understanding of the human condition, where strife and suffering (cf. Hinduism) are the true roots of evil. In certain religious contexts, evil has been described as a supernatural force.  As defined in philosophy it can be the name for the psychology and instinct of individuals which selfishly but often necessarily defends the personal boundary against deadly attacks and serious threats. Definitions of evil vary, as does the analysis of its motives. Elements that are commonly associated with personal forms of evil involve unbalanced behavior involving anger, revenge, fear, hatred, psychological trauma, expediency, selfishness, ignorance, or neglect.
Evil is sometimes perceived as the dualistic antagonistic binary opposite to good, [[CITE|-1|https://books.google.com/books?ct=result&dq=history+yehud+2008&ei=qAMBTNrHBYmlceLa6NUB&hl=en&id=kf9err5bmr4C&lpg=PA131&oi=book_result&ots=LGmPdldLsV&pg=PA131&resnum=2&sa=X&sig=QIbpDXAPWb0nu2lOKXq5o636nuU&source=bl&ved=0CBgQ6AEwATge#v=onepage&q=historyyehud%202008&f=false]] in which good should prevail and evil should be defeated. In cultures with Buddhist spiritual influence, both good and evil are perceived as part of an antagonistic duality that itself must be overcome through achieving Nirvana . The philosophical questions regarding good and evil are subsumed into three major areas of study : Meta-ethics concerning the nature of good and evil, Normative ethics concerning how we ought to behave, and Applied ethics concerning particular moral issues. While the term is applied to events and conditions without agency, the forms of evil addressed in this article presume an evildoer or doers.
Some religions and philosophies deny evil's existence and usefulness in describing people.
The modern English word evil (Old English yfel) and its cognates such as the German Übel and Dutch euvel are widely considered to come from a Proto-Germanic reconstructed form of ubilaz, comparable to the Hittite huwapp- ultimately from the Proto-Indo-European form wap- and suffixed zero-grade form up-elo-. Other later Germanic forms include Middle English evel, ifel, ufel, Old Frisian evel (adjective and noun), Old Saxon ubil, Old High German ubil, and Gothic ubils.
Chinese moral philosophy
As with Buddhism, in Confucianism or Taoism there is no direct analogue to the way good and evil are opposed although reference to demonic influence is common in Chinese folk religion. Confucianism's primary concern is with correct social relationships and the behavior appropriate to the learned or superior man. Thus evil would correspond to wrong behavior. Still less does it map into Taoism, in spite of the centrality of dualism in that system, but the opposite of the cardinal virtues of Taoism, compassion, moderation, and humility can be inferred to be the analogue of evil in it. [[CITE|-1|https://web.archive.org/web/20060529010501/http://www.the-philosopher.co.uk/good&evil.htm]]
Benedict de Spinoza states
- Proposition 8 "Knowledge of good or evil is nothing but affect of joy or sorrow in so far as we are conscious of it."
- Proposition 30 "Nothing can be evil through that which it possesses in common with our nature, but in so far as a thing is evil to us it is contrary to us."
- Proposition 64 "The knowledge of evil is inadequate knowledge." Corollary "Hence it follows that if the human mind had none but adequate ideas, it would form no notion of evil."
- Proposition 65 "According to the guidance of reason, of two things which are good, we shall follow the greater good, and of two evils, follow the less."
- Proposition 68 "If men were born free, they would form no conception of good and evil so long as they were free."
Friedrich Nietzsche, in a rejection of the Judeo-Christian morality, addresses this in two works Beyond Good and Evil and On the Genealogy of Morals where he essentially says that the natural, functional non-good has been socially transformed into the religious concept of evil by the slave mentality of the weak and oppressed masses who resent their masters (the strong).
Carl Jung, in his book Answer to Job and elsewhere, depicted evil as the dark side of God.  People tend to believe evil is something external to them, because they project their shadow onto others. Jung interpreted the story of Jesus as an account of God facing his own shadow. 
Even though the book may have had a sudden birth, its gestation period in Jung’'s unconscious was long.
In 2007, Philip Zimbardo suggested that people may act in evil ways as a result of a collective identity. This hypothesis, based on his previous experience from the Stanford prison experiment, was published in the book The Lucifer Effect: Understanding How Good People Turn Evil. 
Most monotheistic religions posit that the singular God is all-powerful, all-knowing, and completely good.
Polytheistic and non-theistic religions do not have such an apparent contradiction, but many seek to explain or identify the source of evil or suffering.
Non-religious atheism generally accepts evil acts as a feature of human actions arising from intelligent brains shaped by evolution, and suffering from nature as a result of complex natural systems simply following physical laws.
The Bahá'í Faith asserts that evil is non-existent and that it is a concept reflecting lack of good, just as cold is the state of no heat, darkness is the state of no light, forgetfulness the lacking of memory, ignorance the lacking of knowledge. All of these are states of lacking and have no real existence.
Thus, evil does not exist and is relative to man.
"Nevertheless a doubt occurs to the mind—that is, scorpions and serpents are poisonous.
Thus, evil is more of an intellectual concept than a true reality.
Evil in the religion of Ancient Egypt is known as Isfet, "disorder/violence". It is the opposite of Maat, "order", and embodied by the serpent god Apep, who routinely attempts to kill the sun god Ra and is stopped by nearly every other deity. Isfet is not a primordial force, but the consequence of free will and an individual's struggle against the non-existence embodied by Apep, as evidenced by the fact that it was born from Ra's umbilical cord instead of being recorded in the religion's creation myths.
The primal duality in Buddhism is between suffering and enlightenment, so the good vs. evil splitting has no direct analogue in it.
Practically this can refer to 1) the three selfish emotions—desire, hate and delusion; and 2) to their expression in physical and verbal actions.
"What is evil?
In Hinduism, the concept of Dharma or righteousness clearly divides the world into good and evil, and clearly explains that wars have to be waged sometimes to establish and protect Dharma, this war is called Dharmayuddha. This division of good and evil is of major importance in both the Hindu epics of Ramayana and Mahabharata. The main emphasis in Hinduism is on bad action, rather than bad people. The Hindu holy text, the Bhagavad Gita, speaks of the balance of good and evil. When this balance goes off, divine incarnations come to help to restore this balance.
In adherence to the core principle of spiritual evolution, the Sikh idea of evil changes depending on one's position on the path to liberation.
Nevertheless, Sikhism, like many other religions, does incorporate a list of "vices" from which suffering, corruption, and abject negativity arise.
One who gives in to the temptations of the Five Thieves is known as "Manmukh", or someone who lives selfishly and without virtue. Inversely, the "Gurmukh, who thrive in their reverence toward divine knowledge, rise above vice via the practice of the high virtues of Sikhism. These are:
There is no concept of absolute evil in Islam, as a fundamental universal principle that is independent from and equal with good in a dualistic sense. Although the Quran mentions the biblical forbidden tree, it never refers to it as the 'tree of knowledge of good and evil'. Within Islam, it is considered essential to believe that all comes from God, whether it is perceived as good or bad by individuals; and things that are perceived as evil or bad are either natural events (natural disasters or illnesses) or caused by humanity's free will. Much more the behavior of beings with free will, then they disobey God's orders, harming others or putting themselves over God or others, is considered to be evil. Evil doesn't necessarily refer to evil as an ontological or moral category, but often to harm or as the intention and consequence of an action, but also to unlawfull actions.Unproductive actions or those who do not produce benefits are also thought of as evil.
A typical understanding of evil is reflected by Al-Ash`ari founder of Asharism. Accordingly, qualifying something as evil depends on the circumstances of the observer. An event or an action itself is neutral, but it receives its qualification by God. Since God is omnipotent and nothing can exist outside of God's power, God's will determine, whether or not something is evil.
In Judaism, evil is not real, it is per se not part of God's creation, but comes into existence through man's bad actions. Human beings are responsible for their choices, and so have the free will to choose good (life in olam haba) or bad (death in heaven). (Deuteronomy 28:20) Judaism stresses obedience to God's 613 commandments of the Written Torah (see also Tanakh) and the collective body of Jewish religious laws expounded in the Oral Torah and Shulchan Aruch (see also Mishnah and the Talmud). In Judaism, there is no prejudice in one's becoming good or evil at the time of birth, since full responsibility comes with Bar and Bat Mitzvah, when Jewish boys become 13, and girls become 12 years old.
Evil according to a Christian worldview is any action, thought, or attitude that is contrary to the character or will of God.
Christian theology draws its concept of evil from the Old and New Testaments. The Christian Bible exercises "the dominant influence upon ideas about God and evil in the Western world." In the Old Testament, evil is understood to be an opposition to God as well as something unsuitable or inferior such as the leader of the fallen angels Satan In the New Testament the Greek word poneros is used to indicate unsuitability, while kakos is used to refer to opposition to God in the human realm. Officially, the Catholic Church extracts its understanding of evil from its canonical antiquity and the Dominican theologian, Thomas Aquinas, who in Summa Theologica defines evil as the absence or privation of good. French-American theologian Henri Blocher describes evil, when viewed as a theological concept, as an "unjustifiable reality. In common parlance, evil is 'something' that occurs in the experience that ought not to be."
In Mormonism, mortal life is viewed as a test of faith, where one's choices are central to the Plan of Salvation. See Agency (LDS Church). Evil is that which keeps one from discovering the nature of God. It is believed that one must choose not to be evil to return to God.
Christian Science believes that evil arises from a misunderstanding of the goodness of nature, which is understood as being inherently perfect if viewed from the correct (spiritual) perspective. Misunderstanding God's reality leads to incorrect choices, which are termed evil. This has led to the rejection of any separate power being the source of evil, or of God as being the source of evil; instead, the appearance of evil is the result of a mistaken concept of good. Christian Scientists argue that even the most evil person does not pursue evil for its own sake, but from the mistaken viewpoint that he or she will achieve some kind of good thereby.
In the originally Persian religion of Zoroastrianism, the world is a battleground between the god Ahura Mazda (also called Ormazd) and the malignant spirit Angra Mainyu (also called Ahriman). The final resolution of the struggle between good and evil was supposed to occur on a day of Judgement, in which all beings that have lived will be led across a bridge of fire, and those who are evil will be cast down forever. In Afghan belief, angels and saints are beings sent to help us achieve the path towards goodness.
Question of a universal definition
A fundamental question is whether there is a universal, transcendent definition of evil, or whether evil is determined by one's social or cultural background.
The Nazis, during World War II, considered genocide to be acceptable, as did the Hutu Interahamwe in the Rwandan genocide.  One might point out, though, that the actual perpetrators of those atrocities probably avoided calling their actions genocide, since the objective meaning of any act accurately described by that word is to wrongfully kill a selected group of people, which is an action that at least their victims will understand to be evil. Universalists consider evil independent of culture, and wholly related to acts or intents. Thus, while the ideological leaders of Nazism and the Hutu Interhamwe accepted (and considered it moral) to commit genocide, the belief in genocide as fundamentally or universally evil holds that those who instigated this genocide are actually evil. Hitler considered it a moral duty to destroy Jews because he saw them as the root of all of Germany's ills and the violence associated with communism.  Osama bin Laden found it moral to kill all Christians and Jews because he saw Islam as under attack by Western and US influence, accusing the US and Israel of forming a Crusader-Zionist alliance to destroy Islam, and considering US troops in Saudi Arabia infidels in the land of Islam's two holiest sites. He therefore considered non-Muslims and Shiite Muslims evil people intent on destroying Islamic purity and therefore heretic. 
Given his mixed record of efforts to give the Cuban people free-of-charge healthcare and education as well as opposing US hegemony in Latin America, while crushing all opposition and wrecking the Cuban economy, Fidel Castro saw himself as a Caribbean Robin Hood who considered the US and capitalism evil, while Cuban Americans, Cuban dissidents, and other communism-bashing people saw Castro as the personification of evil in late 20th-century Cuban and Latin American history, viewing his Castroist ideology as just as evil as any other form of communism and bashing him for locking up dissidents and killing innocents by firing squads, while creating mayhem in the developing world by working to foment violent communist revolutions in the Americas and many African countries.   
One school of thought that holds that no person is evil and that only acts may be properly considered evil.
Psychologist Albert Ellis agrees, in his school of psychology called Rational Emotive Behavioral Therapy, or REBT. He says the root of anger, and the desire to harm someone, is almost always related to variations of implicit or explicit philosophical beliefs about other human beings. He further claims that without holding variants of those covert or overt belief and assumptions, the tendency to resort to violence in most cases is less likely.
American psychiatrist M. Scott Peck on the other hand, describes evil as militant ignorance. The original Judeo-Christian concept of sin is as a process that leads one to miss the mark and not achieve perfection. Peck argues that while most people are conscious of this at least on some level, those that are evil actively and militantly refuse this consciousness. Peck describes evil as a malignant type of self-righteousness which results in a projection of evil onto selected specific innocent victims (often children or other people in relatively powerless positions). Peck considers those he calls evil to be attempting to escape and hide from their own conscience (through self-deception) and views this as being quite distinct from the apparent absence of conscience evident in sociopaths.
According to Peck, an evil person:
- Is consistently self-deceiving, with the intent of avoiding guilt and maintaining a self-image of perfection
- Deceives others as a consequence of their own self-deception
- Psychologically projects his or her evils and sins onto very specific targets, scapegoating those targets while treating everyone else normally ("their insensitivity toward him was selective")
- Commonly hates with the pretense of love, for the purposes of self-deception as much as the deception of others
- Abuses political or emotional power ("the imposition of one's will upon others by overt or covert coercion")
- Maintains a high level of respectability and lies incessantly in order to do so
- Is consistent with his or her sins. Evil people are defined not so much by the magnitude of their sins, but by their consistency (of destructiveness)
- Is unable to think from the viewpoint of their victim
- Has a covert intolerance to criticism and other forms of narcissistic injury
He also considers certain institutions may be evil, as his discussion of the My Lai Massacre and its attempted coverup illustrate. By this definition, acts of criminal and state terrorism would also be considered evil.
Martin Luther argued that there are cases where a little evil is a positive good. He wrote, "Seek out the society of your boon companions, drink, play, talk bawdy, and amuse yourself. One must sometimes commit a sin out of hate and contempt for the Devil, so as not to give him the chance to make one scrupulous over mere nothings... "
According to certain schools of political philosophy, leaders should be indifferent to good or evil, taking actions based only upon practicality; this approach to politics was put forth by Niccolò Machiavelli, a 16th-century Florentine writer who advised politicians "... it is far safer to be feared than loved."
The international relations theories of realism and neorealism, sometimes called realpolitik advise politicians to explicitly ban absolute moral and ethical considerations from international politics, and to focus on self-interest, political survival, and power politics, which they hold to be more accurate in explaining a world they view as explicitly amoral and dangerous. Political realists usually justify their perspectives by laying claim to a higher moral duty specific to political leaders, under which the greatest evil is seen to be the failure of the state to protect itself and its citizens. Machiavelli wrote: "... there will be traits considered good that, if followed, will lead to ruin, while other traits, considered vices which if practiced achieve security and well being for the Prince."
Anton LaVey, founder of the Church of Satan, was a materialist and claimed that evil is actually good. He was responding to the common practice of describing sexuality or disbelief as evil, and his claim was that when the word evil is used to describe the natural pleasures and instincts of men and women or the skepticism of an inquiring mind, the things called evil are really good.