To Simon how is the pigs head like the devil?

After the hunting party impales the pig's head on a stake outside of Simon's cubbyhole. It is there, in a scene of magic realism that Simon begins to communicate with the head and identifies it as "The Lord of Flies", another name for the Devil. The creature then starts to mock and threaten him, telling him he is not wanted on the island because he represents the soul and spirit of man while the others will likely kill him..