Saul died because he was unfaithful to the LORD; he did not keep the word of the LORD and even consulted a medium for guidance, and did not inquire of the LORD. So the LORD put him to death and turned the kingdom over to David son of Jesse. - 1 Chronicles 10:13-14
God established Saul's kingdom and He then took it away. God elevated Saul and showed him favor, but then removed his hand of favor and demoted him to the point of actually causing his death and the death of all of his sons.
God's Word tells us that this happened to Saul because of his unfaithfulness to the Lord and his disobedience. Saul took things into his own hands and decided to seek the advice and guidance of the wicked instead of trusting in the Lord God. God will not be mocked.
Let's learn from the mistakes of Saul and take note of the character of God. God is love, He is patient, and He is merciful. However, our faithfulness and obedience are also very important. God will accomplish His plans. His kingdom will be established. Let's be people of faith and faithfulness so that we can be part of His plans. Let's turn our eyes, our ears, and our hearts toward Christ every day. Let's be people of faith who trust God for our everything.