Here was David on the back side of the desert. He was being trained for the battles of life. Dear ones, even David, as a young man, yes, he was a youth. He probably didn't have any of the battle scars on him that the old soldiers had.
You notice Saul didn't step up. The Bible tells us earlier, when Saul was chosen king, he was head and shoulders taller than the rest of them. But he didn't stand up to the battle against Goliath and neither did Saul's general. And they were big men. They were men of war.
But David was a youth. His faith started growing in the desert. He watched God work in his life. I can imagine how he feared, being there by himself in the night, the wild animals. He came to faith to believe that, even by watching the sun come up in the morning and the moon and the stars by night, knowing that God had them all named. He put his faith in this God. He hadn't seen Him. But He gave God the credit. Just like he did when he said, "the battle is the Lord's."
I believe we all have to remember this in the days we are going to be going through. The battle is the Lord's.
It doesn't matter how many jet planes and how powerful our military is. God doesn't want us to put our confidence in those things. He wants our confidence to be in Him. Yet we have reason sometimes, and our human nature is to put confidence in men, or military and chariots. And the Bible says, cursed is the man that puts his confidence in a man and blessed is a man who puts his confidence in God.
--Sermon Excerpt: Bro. D.F.