"The plot concerns Robert Wringhim, a staunch Calvinist who believes he is guaranteed Salvation and justified in killing those he believes are already damned by God. The novel has been classified among many genres, including gothic novel, psychological
mystery, metafiction, satire and study of totalitarian thought, it can also be thought of as an early example of modern crime fiction in which the story is told, for the most part, from the point of view of its criminal anti-hero. The action of the novel
is located in a historically definable Scotland with accurately observed settings, and simultaneously implies a pseudo-Christian world of angels, devils, and demonic possession."
I first heard of him - not by name - in chapter ten of George MacDonald's At the Back of the North Wind, in which his most famous long poem, Kilmeny, was quoted from.