William Golding warns people against the practice of evil doing. Discuss.

I have to agree with the previous poster, particularly if you look at the way Simon, arguably the most insightful member of the group of boys, eventually figures out that the "beast" is actually the evil that is within the boys rather than some external creature or parachutist or whatever else.  The fact that Golding gives Simon this realization and then Simon is killed immediately thereafter serves only to emphasize this discovery.

As such, Golding is really pointing out the danger of that evil within us and the fact that without some constraints, it can lead us to do things that are rather terrifying.