Development of the story
The earliest version of this story exists in the Gospel of Mark, described as taking place in "the country of the Gerasenes". Jesus encounters a possessed man, and calls on the demon to emerge, demanding to know its name – an important element of traditional exorcism practice. He finds the man is possessed by a multitude of demons, who give the collective name of "Legion". Fearing he will drive them out of the world and into the abyss, they beg him instead to send them into a herd of pigs, which he does. The pigs then rush into the Lake and are drowned. (Mark 5:1–13)
This story is repeated in the other Synoptic Gospels. The Gospel of Luke shortens it but retains most of the details. (Luke 8:26–33) The Gospel of Matthew shortens it more dramatically, changes the possessed man to two men (a particular stylistic device of this writer) and changes the location to "the country of the Gadarenes". This is probably because the author was aware that Gerasa is actually around 50 km away from the Sea of Galilee (although Gadara is still 10 km distant). In this version, the demons are unnamed.  (Matthew 8:28–32)
The author of the Gospel of Mark could well have expected readers to associate the name "Legion" with the Roman military formation, active in the area at the time (around 70 CE).  The intention may be to show that Jesus is stronger than the occupying force of the Romans. Seyoon Kim, however, points out that the Latin legio was commonly used as a loan word in Hebrew and Aramaic to indicate a large number.
In popular culture
- M. Eugene Boring (2006). Mark: A Commentary. Presbyterian Publishing Corp. ISBN 978-0-664-22107-2.
- Newheart, Michael Willett (2004). My name is Legion: the story and soul of the Gerasene demoniac. Collegeville, MN: Liturgical Press. ISBN 0-8146-5885-7. OCLC 55066538.
- Blount, Brian K.; Charles, Gary W. (2002). Preaching Mark in two voices (1st ed.). Louisville, Ky.: Westminster John Knox Press. pp. 77–78. ISBN 9780664223939.
- Keener, Craig S. (1999). A Commentary on the Gospel of Matthew. Wm. B. Eerdmans Publishing. ISBN 978-0-8028-3821-6.
- Kim, Seyoon (7 October 2008). Christ and Caesar: The Gospel and the Roman Empire in the Writings of Paul and Luke. Wm. B. Eerdmans Publishing. ISBN 978-0-8028-6008-8.
- Senior, Donald (1996). What are They Saying about Matthew?. Paulist Press. ISBN 978-0-8091-3624-7.
- EarlyChristianWritings.com Gospel of Mark, see discussion at bottom of page