The aim of the paper is to show the relationship between the polarity of good and evil in the novel The Brothers Karamazov (Brat'ja Karamazovy, 1880) by Fyodor Mikhailovich Dostoevsky. The emphasis is on the contradictory relationship between Ivan and Alyosha Karamazov since the polarity is the most obvious from this aspect. The first chapter presents the novel by dividing the characters according to the principle of good and evil, and emphasizing the importance of theodicy in whose context the problem of evil is discussed. In addition, the chapters "Rebellion" and "The Legend of the Grand Inquisitor" are analyzed as key to understanding theodicy as well as the teaching of the elder Zosima. The central part of the work is devoted to Ivan Karamazov and his Devil. The issue of freedom and its significance in Ivan's dialectics is problematized, and the crime is represented in the context of the Ivan's downfall. Certainly, the apparition of the Devil in the novel is of special significance, therefore the nature of its appearance and, accordingly, the mode of demonic existence in the novel are being analyzed. The final chapter of the paper is devoted to Alyosha Karamazov, as it emphasizes the importance of his relationship with the elder Zosima as well as Alyosha's spiritual journey ending in spiritual rebirth and return to Christ. Also, the concepts of abstract and active love are presented more closely.