Simon's death was the result of certain individual actions. The savagery of his death is only revealed after all he has witnessed and all he has felt has been realized by the reader. Simon is steadfast in the meaning of his delivery of the truth. However that delievery will never come to fruition, Simon does not have a chance. Simon represents the ultimate sacrifice. It is only with his death that Ralph can see and pursue the idea of survival. For all intensive purposes, (religious or not) Ralph represents at the very least an 'alternative', if there is a chance of hope in 'The Lord Of The Flies', and it is Simon or his spirit that allows whatever hope the boys have left, to finally meet their salvation.
Simon's death is a marker that savagery has taken over almost all of the boys, including Ralph and Piggy. After killing a sow, and eating its meat, all of the boys begin a ritual dance around a fire which builds to a crescendo just as Simon comes down from the mountain with the truth about "the beast". Like Moses, who brought the 10 commandments down from the mountain only to find his people partying with a golden calf, Simon comes down from the mountain with news that "the beast" is simply a dead parachutist. However, he never is able to deliver the news because the boys, seized by their frenzy of eating and dancing, mistake Simon for "the beast" and attack him. They beat and stab him to death, then throw his body out to sea. The next day, only Piggy realizes the this act was murder and when he shares this with Ralph, all Ralph can say it, "There was all this bloody dancing. . . ' But the dancing marks the end of civilized behavior for most of the boys who have now turned into little savages.