The story of David and Goliath is a classic. It highlights the absolute trust a young man had in God. David was not afraid of Goliath and the Philistines.
He was full of faith. His faith had been tested when he killed a lion and a bear all by himself.
According to his words of faith and prophecy, he was able to bring victory to Israel over the Philistines. By faithfully leading the flock of his father Jesse, David learnt how to trust God for bigger situations.
He was able to confront a situation that even King Saul could not confront.