How is the theme good vs. evil evident in the novel Lord of the Flies?

In the novel, there are many examples of good versus evil.
Golding inserts in the novel many Christian symbols--the hit-you-over-the-head kind. For
example, Simon is the Jesus figure: he is kind, works on the huts (Jesus was a
carpenter), feeds the children fruit that they cannot reach (Jesus fed people in the
Bible), and he goes to a private place with natural candles on the trees to meditate
(similar to going to a church to pray). Simon is also the one who has the standoff with
the beast--the boars head on the stick. This is where the beast informs Simon that there
is no beast to be afraid of: they only have to be afraid of themselves--the beast
within.

Furthermore, many experts believe that Jesus had
epilepsy (a seizure disorder), and Simon has this condition, too. He has a seizure at
the end of his conversation with the beast, which is why he has so much trouble walking
down the mountain after he wakes up. He slinks down the mountain, hunched over, and the
kids (at first) mistake him for the Beast. But then they know who it is and they kill
him anyway--good versus evil again. As his body floats away, the head is surrounded by
bioluminescent creatures that make a "halo" around it.

Then
there is Jack versus Ralph. Jack creates a tribe, one that sacrifices animal parts to
the Beast--very reminiscent of young civilizations. Maybe the Beast will be pleased and
won't hurt them if they sacrifice these pigs heads. They have moved from science to
superstition. Jack's henchmen, Roger and Maurice, are as evil as they come. Roger
tortures kids, and he eventually kills Piggy with a large
boulder.

Jack, at the end, reverts to human sacrifice, with
a stick "sharpened at both ends" for Ralph, as he plans on sacrificing Ralph's head to
the Beast. Then Jack's entire tribe hunts Ralph until they are rescued by the adults.
All of the kids, with the exception of Simon, have let their inner beast out on the
island at some point.