What does 1 Samuel 17:45 mean?
David has responded to the Philistine champion's challenge (1 Samuel 17:4–10) and come to fight on Israel's behalf (1 Samuel 17:32, 37, 40). David was not a trained warrior, but he was an experienced shepherd (1 Samuel 17:34–36). He recognized the Philistine's threat as defiance against God (1 Samuel 17:26) and trusted the Lord to bring rescue (1 Samuel 17:37). Goliath has mocked David for coming to challenge him with nothing more than a staff (1 Samuel 17:43), apparently not yet seeing David's sling (1 Samuel 17:40). He has cursed and belittled the virtually unarmed youth (1 Samuel 17:44). This was common battlefield practice intended to break down the spirit of the enemy to make them less confident and effective in the fight.David's spirit remains unbroken. He answers the giant, acknowledging all of Goliath's impressive weapons, including his sword, spear, and javelin. Earlier, Goliath's bronze javelin was described as being slung between his shoulders and his spear as being gigantic with a massive iron point (1 Samuel 17:6–7). The sword was not mentioned in that description, but it will become an important part in the description of Goliath's ultimate fate (1 Samuel 17:51).
David's battlefield proclamation is that he has come to fight Goliath in the name of the God of Israel. By defying Israel's army, the Philistine has been guilty of defying Israel's God. David's opening words leave no doubt that he sees this confrontation as a battle between the Lord God of Israel and Goliath and his gods. Human weapons make little difference.