David asked the men standing near him, “What will be done for the man who kills that Philistine and removes the disgrace from Yisrael? Who is that uncircumcised Philistine that he dares defy the ranks of the living God?” I SAMUEL 17:26 (The Israel Bible™)
David expresses his conviction that the battle against Goliath and the Philistines is far more than an ordinary military affair. Goliath taunts the entire Nation of Israel, and thus by extension, the God of Israel. Defeating him is therefore not only a military necessity, but also a spiritual imperative. David understands that an attack on the People of Israel is always an attack on God Himself, and is prepared to risk his life to defeat Goliath in order to defend the nation and God’s honor. Hashem responds by granting the nation a miraculous victory at the hands of the young David. We see similar stories in our own generation, when the small Nation of Israel has miraculously defeated armies far larger than their own, and whose citizens have frequently seen the hand of God intervening to save Jews from peril.