What is evil? Evil is any force, being or activity that increases human suffering. It is a negative force, concerned with loss and deprivation. It subtracts something from the universe, or interferes with human welfare. Nonetheless evil is relative: what causes pleasure for some may cause pain for others. There are few instances of absolute evil, though some actions and events have come close.

Christian scholars identify three main types of evil: physical, moral, and metaphysical.

Physical evil is that which causes harm to the body or the mind. This kind of evil need not be conscious or deliberate -- a car accident may be an evil event, though there was no bad intent. Similarly we might speak of an "evil storm" on the horizon -- it looks like it will cause suffering, but we don't truly ascribe evil intent to it. Of course, deliberate (unsolicited) bodily injury, or the thwarting of a person's full development, are also evil. The oppression of an underclass is evil because it restricts the development of the members -- again this need not be overt or deliberate to qualify as evil.

Moral evil is deliberate departure from an accepted moral code. This sort of evil can take two aspects. The first is when you do something that you know to be wrong - the will acting against the guidance of the conscience. In this sense moral evil can exist even for the atheist. The second is acting against the precepts of religion - committing sin. Someone who departs unknowing from such codes does not do evil. Thus the "pagans" or "savages" whom Christian missionaries tried to convert did not do evil in the eyes of the missionaries when found "in a state of nature" -- but did do so if they were "converted" to Christianity but then reverted to their native customs.

Metaphysical evil is that which exists due to the structure of the universe. This category generates the most lively debates. Some do not hold that it exists at all - that decay and death are a part of the order of life, and are thus not negative. Others hold that they cause suffering of others, and are thus evil. These latter must then find reasons to justify this kind of evil in the universe of a benevolent God. The Christian solution to this problem is the concept of original sin. The imperfections of the world are a result of Adam and Eve's original mistake in the Garden of Eden.

For Christians, a related topic is the "problem of evil". If God is benevolent, why does He cause or at least permit suffering? This is a topic for another node.