The simplest, and perhaps most prosaic, way to describe ‘The Private Memoirs and Confessions of a Justified Sinner’, written in 1824 by James Hogg, is to refer to it as a psychological tale of a young man, Robert Wringhim, whose religious conviction justifies committing murder. 
Set in early eighteenth-century Scotland, the novel recounts the corruption of Robert Wringhim (a boy of strict Calvinist parentage) by a mysterious stranger under whose influence he commits a series of murders. The stranger assures the boy that no sin can affect the salvation of an elect person. The reader, while recognising the stranger as Satan, is prevented by the subtlety of the novel’s structure from finally deciding whether, for all his vividness and wit, he is more than a figment of the boy’s imagination.