Evil dominates if Good People do nothing .
There are many types of evil, and it is difficult to pin down what good is. For the purposes of this essay I will define good as simply a wish to avert evil, even going out of their way to do so, which in turn I define as something/one who aims to cause seemingly unnecessary suffering to humans. .
Many arguments as to the truth of the statement come from the cause of the different types of evil. Many people refer to moral evil; evil with knowledge of the suffering an action could or will have. Good people can avert this type of evil, but this is not the only way this action would be terminated. A strong argument theists use against the statement is that God, an omnipotent being, intervenes against such people and so this type of evil would not dominate even if good people do nothing. Counter arguments to this are often that reality dis-proves this, as this type of evil go on. Other theists may argue that as God gave humans freewill he does not protect them unreservedly from the consequences of their actions.
Another view on the statement can be gained by looking at the cause of moral evil. Usually the perpetrator has a reason, often viewed as invalid by others, this can be used to further the argument of those who agree with the statement. Two of the most common causes of people committing moral evil are revenge and personal furthement or egoism, in which the individual acts as if he is more important than the others around themselves and act accordingly, causing avoidable suffering in the process. Revenge is the retaliation made by people to a perceived or actual injury. This is evil as it causes suffering which is obviously avoidable with little reward. Both of these modes of thinking are easy and rewarding (to the individual) to use and act on and therefore will only be stopped if good people make active discouragement.
Other types of evil are non-moral and natural evil.