Lyric discussion by NoumenalEnigma 

Cover art for Lord Of The Flies lyrics by Iron Maiden

The lyrics aren't so much summarizing the book but rather expounding on its theme. It's an introspective look onto human nature, and that we all have a dark side to ourselves. "Lord of the Flies" is the literal translation of Beelzebub, or Satan. Both moral and immoral people have an underlying lust for power and an evil side, and without the constraints of society or government, our morals fade away and both "saints and sinners" embrace the darker part of our personality. Humans are intrinsically selfish and evil, no matter how hard we try to try to mask it in society.

My Interpretation