The real message of the battle with Goliath is not that the underdog wins, but that things are not always as they are seen.
.. Yet Saul, whose very selection has been a concession to an insecure populace, proves more attentive to the people who demanded a king than to divine commands.
.. David, by contrast, is accustomed to being underestimated—by his father, by his brothers, by Samuel, and by the king—and perhaps for that reason is able to see beyond appearances. And now he also knows that God has chosen him. Rather than being intimidated into submission by Goliath, he coolly analyzes the giant’s defenses, ascertains his weaknesses, and, presenting himself as a harmless shepherd boy, turns Goliath’s misperception to his advantage.
.. This tension between appearance and reality lies at the heart of the entire story. Here are the words with which Samuel had earlier introduced Saul to the people: “See ye whom the Lord has chosen, that there is none like him among all the people” (10:24). Saul looks fit to be a king, just as Goliath looks like a mighty warrior. But for Saul, as for Goliath, what you see is what you get, and all you get. Indeed, the verb see is used again and again throughout the narrative to highlight a superseded worldview.
.. Nor does David pray to God for help before the duel.