Wikipedia: The Idiot is a novel written by the Russian writer Fyodor Dostoevsky in 1869.
Dostoevsky's motives for The Idiot stem from his desire to depict the "positively good man". This is, of course, likened to Christ in many ways. Dostoevsky uses Myshkin's introduction to the Petersburg society as a way to contrast the nature of Russian society at the time and the isolation and innocence of this good man. This is highlighted by his conflicts and relationship with Rogozhin. Indeed, Myshkin and Rogozhin are contrasted from the outset. Myshkin is associated with light, Rogozhin with dark. For example, in their initial descriptions on the train, Myshkin is described with light hair and blue eyes, Rogozhin with dark features. Rogozhin's house is dark, with iron bars on the windows. He is not only an embodiment of darkness, but surrounded by it. The two are utterly antithetical. If Myshkin be seen as Christ, Rogozhin would be the devil. Indeed, 'rog', in Russian, means horn, which adds credence to such an assertion. However, they are both after Nastasya Fillipovna - good and bad strive for the same thing. But Rogozhin kills Nastasya. The materialistic society of Russia was one that praised the values Myshkin represents; however, Rogozhin, though he loves Nastasya, commits murder in the end. This parallels society; while it professes to be "good", it cannot accommodate Prince Myshkin. Nastasya herself has been corrupted by a depraved society. Her beauty has led to Totsky, perhaps the most repugnant of characters in the novel, keeping her as a concubine and she falls into a quasi-madness. Love itself is shown in various manifestations, spurned by various motives. While vain Ganya wishes to marry Nastasya in order that he might, through acquisition of a large dowry, spark some of the individuality which he senses he lacks, Rogozhin loves Nastasya with a deep passion- a passion which drives him to kill her. Myshkin, however, loves her out of pity, out of a Christian love. But his love for her supersedes the romantic love he has had for Aglaya.