1 Samuel 16:13

Then Samuel took the horn of oil and anointed him [David] in the midst of his brothers; and the Spirit of the Lord came mightily upon David from that day forward.
1 Samuel 16:13

God’s calling is always accompanied by the Spirit’s enabling.

This truth follows directly upon the previous observation. In every respect, David was a most unlikely candidate for the throne of Israel. Most of us are so blinded by our knowledge of David’s subsequent greatness that we fail to consider who he truly was at the outset – an unknown boy, a shepherd with a questionable family pedigree, who lived in a small town up in the hills. [Remember: David had a lot of Canaanite in him. His grandmother was Ruth, a Moabitess, and his great-grandmother was the Canaanite , Rahab.]
And yet, this boy’s name would soon be on the lips of all Israel and he would quickly distinguish himself as a mighty warrior, a gifted musician and composer, a charismatic leader and a capable administrator and judge. In time, David would become the archetypical leader of God’s covenant people – the one against whom all subsequent kings of Israel and Judah would be measured. And in addition to this, David wrote as a prophet of Almighty God and would receive God’s covenant promise of a descendent who would rule forever. He stood for over a thousand years as the Biblical picture of the Messiah until the prophecies were fulfilled through the coming of his greater descendent, Jesus Christ.
But all of that lay in the future for this young man. On that momentous day, he had no way of knowing what he would become, nor did he grasp that he was a linchpin in God’s plan of redemption. So as Samuel departed, David stood there in his parents’ house under the skeptical scrutiny of his brothers. And with the anointing oil dripping into his eyes, he no doubt wondered, “Why me?” Most likely, right on the heels of that question came a stab of doubt: “How in the world can I fulfill this calling?” It’s a question many of us have asked as well.
We find the answer to David’s dilemma and the explanation for all of his subsequent greatness in this verse. Here, at the very beginning of his public life, David was empowered by the Spirit. God not only called David, He also enabled him for the work ahead of him. Notice the deliberate contrast in 1 Samuel 16 between David’s empowering by the Holy Spirit and the fact that Saul – the king God had forsaken and whom David will replace – has been deserted by that same Spirit. The very next verse (v. 14) says, “Now the Spirit of the Lord departed from Saul…” The presence of the Holy Spirit is the key to David’s greatness.
Consider that David’s wide-ranging abilities, his “renaissance man” character, stemmed directly from the powerful presence of the Holy Spirit in his life. As the subsequent chapters will show, the Spirit-produced difference in David was remarkable. His giftedness began to flower immediately, and his gifts opened a place for him at Saul’s court, winning him a reputation as a great warrior and leader. God had called David to be king, and the Holy Spirit worked mightily in him and through him to bring that call to fruition.
Now, I will leave to the theologians the minutia of the differences between the work of the Spirit in the Old Testament and His ministry in the New Testament. At this point, we simply need to grasp that the Holy Spirit has ALWAYS been the One who enables and empowers God’s people. Whether we consider David, or the prophets (Is. 61:1), or the early church (Acts 2:4, 4:31), the empowering of the Spirit has always been essential for doing God’s work. Christ Himself received and relied upon the Spirit’s power in His ministry (Lk. 4:1). [In fact, the parallel between David’s anointing and Christ’s baptism is remarkable: both were unknown and unremarkable, both appeared unexpectedly, both were set apart as God’s king by God’s prophet, both were empowered by the Holy Spirit, and both would soon have their faith tested.]And what was true of David is also true of all of us who trust in “the son of David.” The Spirit gives us a new heart and causes us to walk in faith (Ezek. 36:26,27), and He empowers us with spiritual gifts for the good of the church as He extends Christ’s Kingdom through us (Rom. 12: 6-8; 1 Cor. 12:7ff; Eph. 4:11-16). Yes, He often calls us to tasks that are beyond our ability. Yet, here is the wonder: God’s people are never left to their own resources as they do God’s work (Phil 1:6, 2:13). You are not alone; Christ has not left you as an “orphan” (John 14:18). Although none of us is adequate in ourselves, the sovereign Holy Spirit works in us and through us to accomplish the Father’s will (2 Cor. 3:5,6; Rom. 8). So God receives all the glory

1Samuel 16:1

Now the Lord said to Samuel, “How long will you grieve over Saul, since I have rejected him from being king over Israel? Fill your horn with oil and go; I will send you to Jesse the Bethlehemite, for I have selected a king for Myself among his sons.”

1 Samuel 16:1

God chooses unlikely vessels for great tasks.

Here is the beginning of the Bible’s account of David’s history. Aside from those things mentioned later, we know very little of his boyhood or of his personality before this seminal event. It’s as if David suddenly leaps onto the stage of Biblical history – an unknown shepherd boy who was completely unaware of God’s plans for him. Yet, God is not surprised; He has already chosen David: “I have selected a king for Myself…”

Is it possible that God’s wording here refers back to the selection of Saul? Remember that the people had insisted to Samuel that they wanted a king like all the other nations around them (see 1 Samuel 8:4-9). And Saul, with his handsome bearing and imposing stature seemed to be every inch the king. Yet it wasn’t long before Saul began to demonstrate his true character and to fulfill the dire prophecies Samuel had spoken to Israel in 1 Samuel 9: 10ff. Eventually, due to his disobedience, Saul was rejected by God as king: “And as Samuel turned to go, Saul seized the edge of his robe, and it tore. So Samuel said to him, ‘The Lord has torn the kingdom of Israel from you today, and his given to your neighbor who is better than you.’” It’s almost as if God said, ‘Since you insist on a king, I will choose one for you who will fit My requirements.’ David’s history, then, began with a sovereign choice of God – a choice that determined the course of his entire life from that time forward.

We can’t be entirely certain, but it is likely that David was a teenager at this point – too insignificant to even be considered in such “great affairs.” His father left him watching the sheep when he called all the other brothers to Samuel’s sacrifice. It seems that Jesse never even thought of David as part of this momentous event. For Samuel’s part, he continued to focus on outward appearance, and was ready to anoint David's older brother on the spot – until God corrected him. “God sees not as man sees, for man looks at the outward appearance, but the Lord looks at the heart.” (1 Sam. 16: 7)

And it’s here that we see God’s criterion for usefulness – the one characteristic that fits men and women for great tasks. Although he was physically handsome, David was largely unremarkable and without great gifts or pretensions. It was David’s heart that appealed to the Lord. We are told in 1 Kings 11:4 that his heart was “wholly devoted to the Lord his God.” It was this heart for God that, on the human level, provided the foundation for all his later accomplishments. The contrast here is deliberate: Saul appeared to be all a king should be and failed at every turn; David gave no outward evidence of kingliness, but his efforts were blessed by God throughout his reign.

This is the pattern all through Scripture and also in the history of the church. God consistently has chosen to work through the unimpressive, the unremarkable, the unknown, and the uneducated. (See 1 Cor. 1:26; 2 Cor. 4:7; 12:9) He has accomplished remarkable things through an impulsive fisherman, a former persecutor of Christians, a bipolar German monk, a converted slave trader, a depression-plagued evangelist, a teenaged preacher, etc. The examples are legion. The outward condition of the willing vessels makes no difference, since it’s the omnipotent Holy Spirit who does the work through them. As the Lord said to one of David’s descendents, “the eyes of the Lord move to and fro throughout the earth that He may strongly support those whose heart is completely His.” (2 Chron. 16:9)

So what’s the best way to prepare ourselves for God’s use? While there is nothing wrong with pursuing education and training, such things should never divert our attention from pursuing a heart for God. Frankly, without this wholehearted devotion to God, it matters very little how educated, skilled or doctrinally orthodox we are. But if you have been given a heart like David’s, be assured that God will use you for His glory – regardless of your age, status, location or disability. God loves to do great things through unlikely vessels.