For a novel that ponders the ability of the "perfectly beautiful" person to have any kind of lasting impact on others, there is a significant amount of space in The Idiot devoted to the contrasts in the battle between good and evil. Usually, the symbols of these two forces are comparable but opposing characters who shed some light by providing stark contrasts. But, because this is a complex novel, and not a morality play, things aren't that simple.
In this novel, the concepts of good and evil exist primarily through contrasts between two things that would not necessarily appear either good or evil without a juxtaposed counterpart.
The novel is obsessed with murder and the state of mind that allows someone to kill another human being. The evil associated with murder attains supernatural levels.