Apostle Rope is used by religious people to punish thmselves by flogging in a futile effort to make the dome go away in Under the Dome.
Under the Dome[]
Apostle Rope is described by Lester Coggins as "a heavy length of rope that had been knotted twelve times" in his self-flagellation.
The twelve knots represented the twelve apostles; the ninth knot, representing Judas Iscariot, "had been painted black."
Coggins used the rope to whip himself bloody on the night of Dome Day, after which he experienced an auditory hallucination that he believed was the voice of God, leading him to read Deuteronomy 28:28-29.