How can I explain the "coming of age" theme in The Lord Of The Flies?
One of the major reasons that Golding wrote The Lord of the Flies was to present a picture of what would happen if innocent boys were placed on an island alone without the influence of society or rules or adults. This also gives them the opportunity to "come of age" without those same influences and his novel was intended as an examination of how that might work.
In this case, the conclusions of this study are not very optimistic given that the boys struggle mightily with the idea of social order and justice and, just before the boys are rescued, it appears that they have grown up to become savage and brutal. Rather than listen to the boys that represent law and order (Ralph and Piggy), the boys have been drawn to Jack's band of hunters and their wild ways. Because he can supply their desire for meat and excitement, they forego a willingness to be organized, to work together, to create a lawful society like the one they were part of before coming to the island.