Evil is whatever frustrates or opposes goodness, and goodness is what is, or ought to be, desired by conscious rational agents. Suffering is thus one sort of evil, since no conscious rational agent would desire to suffer, just for its own sake. Other sorts of evil lie in the frustration of the aims and goals of rational agents (one might also include the aims of God, and some would include the aims and goals of any beings whatsoever, insofar as they could reasonably be said to have aims or goals), or in factors that restrict the normal activities and dispositions of rational or sentient agents.

Buddhism

The faith that most obviously takes the fact of evil as one of its basic starting points is Buddhism, whose first noble truth is that "all is suffering" (dukkha). This is not merely the view that there is much frustration and suffering in life. It is...