"Every Death Eater had the sign burned into him by the Dark Lord. It was a means of distinguishing one another, and his means of summoning us to him." -Professor Snape, Book Four, p. 710
Voldemort's followers, called Death Eaters, bore the Dark Mark on their bodies as a sign of allegiance to the Dark Lord. They openly followed him when he was in power, but after his downfall many claimed they had been acting against their will. Some were convicted and put in Azkaban. Many blended back into the wizarding population.
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The Dark Mark was also used to call the Death Eaters to Voldemort whenever it became visible on their bodies. Both Karkaroff and Professor Snape had been troubled because the mark they bore had become more and more pronounced throughout the Triwizard Tournament. Snape's full story has yet to come out, but we know he had been a Death Eater who renounced his involvement with Voldemort, made a turnaround and-somehow-gained Dumbledore's trust. Dumbledore even accepted him as a teacher at Hogwarts. However, his experience with the Dark Arts left its mark-which he can hide, but apparently not erase entirely.
When one thinks of a "Dark Mark" in biblical terms, one might recall "the mark of the beast," which Revelation says is a mark that will be put on those aligned with the antichrist before the last battle. However, there are significant differences that make a correlation between the Dark Mark and the mark of the beast only serve as a secondary parallel at best. There is another parallel that is more in keeping with the story line of the Harry Potter books, and goes more directly to the heart of the gospel. It calls us to focus our attention on Professor Snape.
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