When David volunteered to slay Goliath, right from the very outset, his method and aim were straight and sure. He recognized his God-given ability to accomplish this task, knew that his tools were effective and that by aiming straight at the target he would destroy the foe.
We have come to recognize Goliath as representing evil, or error. Whether or not David saw his opponent this way, his confidence in God enabled him to face the giant fearlessly, his motive being to save Israel. He did not question whether he could or should undertake this challenge. He knew that God had already furnished him the means for accomplishing the task.
This, then, leads us to the method David used in slaying Goliath. Did he rely on the means or suggestions of others, however well meant? According to the biblical account, he told Saul he could not use the king's armor because he had not proved it. He had already proved the effectiveness of sling and stone in protecting his flock and himself from the lion and bear. But he also knew the nature of true safety. He said, "The Lord that delivered me out of the paw of the lion, and out of the paw of the bear, he will deliver me out of the hand of this Philistine." I Sam. 17:37.