In Lord of the Flies, William Golding is conveying the message that human beings must have rules, authority and government in order to maintain a safe environment.
Left to their own, with freedom from discipline, rules, and governmental regulations, Jack and his tribal warriors return to animal instincts. They lose respect for human life. Jack and his boys are so free from control until they have lost their sense of right and wrong. They get carried away in the frenzy of the hunting dance until they attack Simon and kill him with their bare hands and teeth.
Likewise, Roger, one of the most vicious of Jack's hunters is losing his respect for human life and throws rocks at Piggy, thus sending him down to his death into the rocks below in the sea.
Without rules, authority and government, the boys become disorderly, vicious, and evil. Golding proves that mankind needs some form of government with authority figures enforcing the rules. Golding proves the utter chaos that can happen in a society which is not governed.
Golding's message throughout the novel Lord of the Flies is that fear is the catalyst for violence and the destruction of civil societies. Fear is a major theme throughout the novel and is the reason behind the boys' loss of innocence. The boys fear what they do not understand, and Jack uses this fear to convince the majority of the boys to join his tribe. The boys fear the unknown "beastie" and look towards Jack and his hunters for protection. When Simon comes out of the forest, they mistake him for the beast and brutally murder him out of fear. Jack underminds Ralph's leadership by calling him a coward because he was scared to go first up the mountain to look for the beast. When Jack gains control of the boys, he uses fear and intimidation to control them. Golding draws comparisons to totalitarian governments who use similar methods to control their populations. Golding suggests that fear is an inherent quality in humans and portrays the damage irrational fears can have on individuals and society.
The message that Golding is trying to convey is that it is hard, if not impossible, for human beings to ultimately master their more primitive and savage instincts. Even when there is an attempt at maintaining order, civilized society and social co-operation, it is liable to break down. This idea of the primitive savage and anarchic tendencies of humans lying under a veneer of civilization is one that is common to much modern literature, particularly in the period around the two world wars and the specter of a potential nuclear holocaust. This, of course, is when Lord of the Flies was written.
Golding chooses to convey this message by portraying what happens when a marooned group of boys try to set up their own society. In the end, this valiant attempt is overrun by the forces of chaos when the violence of Jack and his hunting group takes over. Golding simply narrates what happens and doesn't make any direct statement of the theme. He lets the grim action of the book speak for itself and also inserts some symbolism in the form of the sow's head, the "Lord of the Flies" - a euphemism for the devil - which the visionary Simon imagines is speaking to him.
Although Golding focuses on boys rather than adults, what happens to the boys also mirrors what has happened in the world of adult civilization: they are marooned in the first place as the result of a global conflict.