The reading for today, 1 Samuel 29-31, brings us to the end of this book. Bob Deffinbaugh offers this encouraging commentary at Bible.org-
God’s sovereignty is so apparent in the rescue of David and his men from military service, service to the Philistines and against Israel. God uses David and even his sin to achieve His ultimate purposes. God does not cause David to sin, nor is this sin excused. But in the end, God’s sovereignty (absolute control) is so great that He can even employ the disobedience and sins of men to further His own purposes. He used the sinful betrayal of Joseph by his brothers to save the nation Israel. So God uses sinful men in our text. He used David, as we have seen. He uses the naivet of a king like Achish and the foresight and practical wisdom of the four Philistine commanders. He will even use the Amalekite attack for a good purpose. I love what Davis says about God’s use of His enemies:
“We see it again. What instruments does Yahweh use to rescue his servant from his dilemma? The commanding officers of the Philistine army. It was not the first time Yahweh had turned enemies into saviors (see 23:19-28). Philistines make such unwitting but effective servants! Who has ever been his counselor?! (Cf. Isa. 40:13-14).”158
“What our text does teach is that even in our folly and fainting fits, we are still no match for our God, who has thousands of unguessable ways by which he rescues his people – even by the mouths of Philistines. He can make the enemy serve us as a friend. He not only prepares a table for us in the presence of our enemies but also has the knack of making the enemies prepare the table!”159
I think we sometimes unthinkingly assume God is a saving God only at the cross of Calvary. The fact is that God has been and still is a saving God. He has been saving men from the beginning of history. God is a rescuer. He rescued Noah and his family from the flood (Genesis 6-9). He rescued Abram from Egypt and from the hand of Abimelech in Gerar (Genesis 13, 20). He rescued Lot and his daughters from Sodom and Gomorrah (Genesis 19). He rescued Jacob and his family from extinction as a separate nation (Genesis 37ff.). He rescued the Israelites from Pharaoh, and from the evil hand of many other kings and nations. He constantly rescued the Israelites from their surrounding enemies during the days of the judges. If God needed practice in saving men (which He most certainly does not!), He would be very good at it by now.
But all of these earlier deliverances do not hold a candle to the great and final act of deliverance that He brought about for men in the sacrificial death, burial, and resurrection of Jesus Christ. He died for our sins, bearing our punishment. He not only takes our sins upon Himself, He offers His righteousness to us so that we may have eternal life and dwell with Him for all eternity. And God accomplished this through the sinful betrayal of Judas, the jealousy and scheming of the Jewish religious leaders, the cooperation of Gentile Roman rulers (who sought to be politically correct), and the passivity (and even participation) of the people. This He did so that sinful men might be forgiven for their sins and receive the righteousness which God offers to us in the person of Jesus Christ.