The four defenses of David in this chapter can be seen as four defenses of Christ, of the gospel itself, by Christians and by the Holy Spirit.
And Saul spoke to Jonathan his son and to all his servants, that they should kill David. But Jonathan, Saul's son, delighted much in David. And Jonathan told David, “Saul my father seeks to kill you. Therefore be on your guard in the morning. Stay in a secret place and hide yourself. And I will go out and stand beside my father in the field where you are, and I will speak to my father about you. And if I learn anything I will tell you.” And Jonathan spoke well of David to Saul his father and said to him, “Let not the king sin against his servant David, because he has not sinned against you, and because his deeds have brought good to you. For he took his life in his hand and he struck down the Philistine, and the Lord worked a great salvation for all Israel. You saw it, and rejoiced. Why then will you sin against innocent blood by killing David without cause?” And Saul listened to the voice of Jonathan. Saul swore, “As the Lord lives, he shall not be put to death.” And Jonathan called David, and Jonathan reported to him all these things. And Jonathan brought David to Saul, and he was in his presence as before. (1 Samuel 19:1-7)
The first defense is the verbal defense. Paul wrote that he was put here for the defense of the gospel. Peter tells us to always be prepared to make a defense to anyone who asks us for a reason for the hope that is in us. This may only be a link in the chain that will convert a soul to Christ, but each link is necessary, and we should always try to engage a hostile world in fruitful discussion about the truth as found in Jesus Christ.
And there was war again. And David went out and fought with the Philistines and struck them with a great blow, so that they fled before him. Then a harmful spirit from the Lord came upon Saul, as he sat in his house with his spear in his hand. And David was playing the lyre. And Saul sought to pin David to the wall with the spear, but he eluded Saul, so that he struck the spear into the wall. And David fled and escaped that night. (1 Samuel 19:8-10)
Sometimes we forget that Jesus can defend himself! As we read in Luke 4, "When they heard these things, all in the synagogue were filled with wrath. And they rose up and drove him out of the town and brought him to the brow of the hill on which their town was built, so that they could throw him down the cliff. But passing through their midst, he went away." Nothing is going to happen to Jesus, because he is God's son, and God is sovereign. Even Christ's death on the cross was planned from the beginning and was preformed for the salvation of the souls of God's children, because he loves us. He is willing to put himself at disadvantage for our sakes, but God is always in control. Not a sparrow falls without him knowing about it.
Saul sent messengers to David's house to watch him, that he might kill him in the morning. But Michal, David's wife, told him, “If you do not escape with your life tonight, tomorrow you will be killed.” So Michal let David down through the window, and he fled away and escaped. Michal took an image and laid it on the bed and put a pillow of goats' hair at its head and covered it with the clothes. And when Saul sent messengers to take David, she said, “He is sick.” Then Saul sent the messengers to see David, saying, “Bring him up to me in the bed, that I may kill him.” And when the messengers came in, behold, the image was in the bed, with the pillow of goats' hair at its head. Saul said to Michal, “Why have you deceived me thus and let my enemy go, so that he has escaped?” And Michal answered Saul, “He said to me, ‘Let me go. Why should I kill you?’” (1 Samuel 19:11-17)
Christ is defended in the life of the church. Through the service, the preaching, the sacraments, the love for the surrounding community, the church confounds the hating world by using the foolish things of God.
When many days had passed, the Jews plotted to kill him, but their plot became known to Saul. They were watching the gates day and night in order to kill him, but his disciples took him by night and let him down through an opening in the wall, lowering him in a basket. (Acts 9:23-25)
Christ is hidden within the church, but once the church acts, he is revealed to all who seek him.
Now David fled and escaped, and he came to Samuel at Ramah and told him all that Saul had done to him. And he and Samuel went and lived at Naioth. And it was told Saul, “Behold, David is at Naioth in Ramah.” Then Saul sent messengers to take David, and when they saw the company of the prophets prophesying, and Samuel standing as head over them, the Spirit of God came upon the messengers of Saul, and they also prophesied. When it was told Saul, he sent other messengers, and they also prophesied. And Saul sent messengers again the third time, and they also prophesied. Then he himself went to Ramah and came to the great well that is in Secu. And he asked, “Where are Samuel and David?” And one said, “Behold, they are at Naioth in Ramah.” And he went there to Naioth in Ramah. And the Spirit of God came upon him also, and as he went he prophesied until he came to Naioth in Ramah. And he too stripped off his clothes, and he too prophesied before Samuel and lay naked all that day and all that night. Thus it is said, “Is Saul also among the prophets?” (1 Samuel 19:18-24)
Finally, there's the defense of conversion by the Holy Spirit. Ultimately, it is God's choice who "gets it" and who doesn't. As the church, we cast seeds of apologetic before the world, which either will reject it or incorporate it into its understanding of truth. In the end, the Holy Spirit is who changes the heart of the unbeliever into a spirit-filled believer. As in Acts 9, Saul is breathing murder against the disciples, and in that time of hatred, he is dethroned from his own personal kingdom and Christ himself assumes the place of power.
In Acts 2, we have all four of these defenses at work: the Holy Spirit breathing life into the new believers, a well-reasoned defense of The Way by Peter, the fellowship of the church, and Christ's safe interceding from heaven. The dynamic of the church, the truth, the Spirit, and Christ is such that we should never have qualms about sharing the hope that is in us. Though faith, we can help Christ draw the world toward himself.