1 Samuel 16:7 KJV

When God chooses David to be anointed king of Isreal, he chooses the weakest, shortest, and youngest of Jesse's sons, saying "man looks at the outward appearance, but the Lord looks at the heart." However, when Saul is anointed, he certainly looks like someone who could be a king. So why did God's apparent method of selecting a future king change?

I have a theory about this. God certainly knew, when he chose Saul, that Saul would eventually disobey him and have the throne taken away from his descendants. (He does remain king himself for the rest of his life, probably because he turns back to God when he realizes he has sinned. But the damage had already been done, so the throne could not be passed to Saul's sons.) In a nutshell, Saul was every bit the king that Isreal wanted.

I think that God used Saul to show the Isrealites what would happen if they actually got all they wanted. He was furious that they even wanted a king in the first place, since it showed that they really didn't trust God to lead them. God was their king, why did he need to be supplemented with a totalitarian earthly leader? So God decides to give them the king they wanted.

The next time around, though, it's different. God chooses someone that no one, not even the prophet Samuel would have selected. I think David was the ancient Isreal equivalent of an artsy kid today. He was a poet, a musician, and fought his battles not with brute force, but with faith and precision. This time, God picked the king he wanted, not the one Isreal wanted. And the funny thing is, he turned out to be the most renowned king in Isreal's history, forever known as a man after God's own heart.