Seviin Sick Sins: The Compleat Attrocities by Kevin Sweeney

On the dark web's premier social media site, a new sensation has gone viral with the psychopaths. He calls himself the Disciple of Iscariot, and his insane followers are the Four Final Things. He preaches a deranged creed that "in excess shall ye find salvation", and forces kidnapped sinners to commit atrocities of the flesh in order to save their souls.

Trigger warnings? ALL OF THEM.

Containing the entire saga in one novel-length book, including:
NECRO-SUTRA

THE LUSTY
THE GLUTTONS
THE SLOTH

THE GREEDY & THE ENVIOUS
THE ANGRY
THE PROUD