It's essentially a story of a small child (David) going against a giant (Goliath). Everyone claimed that David would die if he were to battle Goliath. David ended up using a sling shot, hit him right between the eyes and killed him, then cut off his head as proof. And a lot of Halo was based on the bible, even the David & Goliath story is kind of the theme overall arching story in Halo. Humanity is David & The Covenant were/is Goliath.