The story of David and Goliath, from the first book of Samuel, is a favorite of many.
The Philistine and Israelite armies faced each other in war on opposite sides of a steep valley. An armored Philistine giant named Goliath, who stood over nine feet tall, came out each day for forty days, mocking and challenging the Israelites to fight, but they were all terrified to meet his challenge.
One day a boy named David was sent to the battle front by his father to bring back news of his brothers. While there, David heard Goliath's boastful challenge and volunteered to fight him. The other Israelites tried to dissuade him, but he insisted on fighting the giant.
Dressed only in a tunic and carrying a shepherd's staff, David took only his slingshot and a pouch full of stones as a weapon against the giant. Goliath taunted him, but David called out, "You come against me with sword and spear and javelin, but I come against you in the name of the Lord Almighty, the God of the armies of Israel, whom you have defied."
As Goliath approached, David slung a stone that smashed the giant's forehead, causing him to fall face-down on the ground. David then killed Goliath with his own sword and cut off his head. The Philistines saw the dead giant and fled. The Israelites pursued and conquered them.
David's faith allowed him to look at the giant from a unique perspective. Goliath was a mortal man defying God. When we are right in our cause when battling a formidable foe, God will fight for us. David took such action against Goliath, and had complete faith in God. He wished only to carry through the will of his Creator. He was obedient - willing to sacrifice everything that he had for the Lord. He knew that only the wishes of God were important - everything else shrunk to nothing in comparison.