I agree with Katie, this is truly a great work of literature. The main theme of Lord of the Flies is the juxtaposition of human civilization vs. savagery (represented by Jack and Ralph). The story claims that without the constraints and controls of society, humans will ultimately revert back to pure savagery. Civilization is not just an important part of our world, but a necessary piece of control that keeps humans moving in a forward pattern.
Lord of the Flies is such a fabulous read! The two most obvious themes are loss of innocence and nature/human instinct vs. societal norms. While stranded on the island, the young boys go from functioning members of society (i.e. well-behaved, polite, considerate) to cruel savages. During this drastic change, the boys lose their innocence by retreating to basic animalistic instincts (survival mode) and foregoing everything that they have been taught about how they “should” behave. These ideals are portrayed throughout the novel, and they support the claim that when humans – even seemingly innocent children – are left to our own devices, we naturally retreat to evilness and barbarism. Hope this helps!