What point was Golding trying to make when he posed the question," You knew, didn't you? I am part of you?" through the beast's/ lord of the flies' mouth?

 The Lord of the Flies or Beelzebub (Devil) manifests itself in the form of a pig's head on a stick. Simon, our Christ figure, is trying to reconcile the darkness in mans’ heart. The beast tells Simon, in the authoritative tone of a schoolmaster, that he can never run away from evil because evil exists inside of him. Evil is mans' essential illness that he is born with. The voice tells Simon he can run away but he cannot run away from himself. Simon must face his internal fear of evil in order to overcome it.