What two mistakes did Saul make that cost him his dynasty and his kingdom?

Answer 1

Saul had more of a fear of man than he did of God: This is seen time and again as he does not follow the commands of God, but compromises out of his own insecurity.

The two key moments in his being rejected by God as king are the following stories:

1 Samuel 13 - Disobedience to the Mosaic Law

While waiting for Samuel to show up, Saul gets impatient and worried about his soldiers leaving. He disobeys the Mosaic law and (being a non-priest), offers the burnt offering - which was an unlawful act - only priests are allowed to do this. He then tries to make excuse for himself (1 Samuel 13:8 - 12)

1Sa 13:13 And Samuel said to Saul, "You have done foolishly. You have not kept the command of the LORD your God, with which he commanded you. For then the LORD would have established your kingdom over Israel forever.

1Sa 13:14 But now your kingdom shall not continue. The LORD has sought out a man after his own heart, and the LORD has commanded him to be prince over his people, because you have not kept what the LORD commanded you."

1 Samuel 15 - Disobedience to the command of God

Saul is commanded to completely destroy the Amalekites and leave nothing.. not even animals (this is a topic for another question)

Saul once again half-obeys and keeps the animals alive and a few of the people. And then again makes excuses for himself.

It seems that Saul caved in to pressure from his soldiers who were wondering why cant we keep some of the spoil.

1Sa 15:24 Saul said to Samuel, "I have sinned, for I have transgressed the commandment of the LORD and your words, because I feared the people and obeyed their voice.

God's response is seen in 1 Samuel 15:26 - 28

1Sa 15:26 And Samuel said to Saul, "I will not return with you. For you have rejected the word of the LORD, and the LORD has rejected you from being king over Israel."

1Sa 15:27 As Samuel turned to go away, Saul seized the skirt of his robe, and it tore.

1Sa 15:28 And Samuel said to him, "The LORD has torn the kingdom of Israel from you this day and has given it to a neighbor of yours, who is better than you.

Saul was rejected because of poor leadership and disobedience to the Word of the Lord.