"the guy I like best in the Bible, next to Jesus, was that lunatic and all, that lived in the tombs and kept cutting himself with stones."

 This man lived in the tombs, and no one could bind him any more, not even with a chain. For he had often been chained hand and foot, but he tore the chains apart and broke the irons on his feet. No one was strong enough to subdue him. Night and day among the tombs and in the hills he would cry out and cut himself with stones. Mark 5:3-5

The lunatic is Legion, so-called because he is possessed by a legion of demons, who force him to live apart and injure himself.  Jesus calls the demons out, and they possess instead a herd of 2,000 pigs who promptly drown themselves.  Quite a few innocent pig farmers were ruined by divine intervention that day. 

There is a parallel to Holden's own demons and disconnection.