Israel has not heard from God in decades. The priests are corrupt and nearby nations threaten the land’s safety. Even Eli, the high priest and judge of Israel, is not faithfully serving God and the people. God gives Israel Samuel.
Samuel begins as a judge and a prophet. He speaks the word of the Lord and teaches the people how to live as the people of God. But when Samuel grows old and Israel’s enemies attack, the people demand that Samuel appoint a king. Samuel advises the people to trust in God and not in human leadership. However, the people are determined to have a king rule over them and deliver them from the enemy, so God gives them Saul.
Saul is a selfish and cowardly king who ignores the word of the Lord and craves the approval of men. He disobeys God and puts the people at odds with God and each other. He does not follow the Law of Moses and does not direct the Israelites to live as holy people. As a result he comes to an ignominious end.
After this, God gives Israel David, who He finds "a man after [God’s] own heart."David is a skilled warrior, musician, and leader, and he trusts in God and encourages his countrymen to act like God’s people. His famous defeat of Goliath makes him a popular figure in Israel, causing Saul to fear him and spend much of his life hunting David down.
The books of 1 and 2 Samuel are really one story and were not originally divided. First Samuel marks a great turning point in Israel’s history as it transitions from theocracy to monarchy. Instead of crying to God for help, Israel demands that Samuel appoint a king. It is in 1 Samuel that we first see an example of Messiah (God-anointed royalty). Saul and David are anointed by God to lead and deliver Israel. This points toward Jesus, a descendant of David (Mt 1:1), who is to be the true Messiah anointed by God to rule over all (Philippians 2:10–11) and save the lost (Acts 13:38).