Why did Saul want to kill David?
1 Samuel 18:8-9
8 And Saul was exceeding angry, and this word was displeasing in his eyes, and he said: They have given David ten thousands, and to me they have given but a thousand; what can he have more but the kingdom? 9 And Saul did not look on David with a good eye from that day and forward.
1 Samuel 18:12-15
12 And Saul feared David, because the Lord was with him, and was departed from himself. 13 Therefore Saul removed him from him, and made him a captain over a thousand men, and he went out and came in before the people. 14 And David behaved wisely in all his ways, and the Lord was with him. 15 And Saul saw that he was exceeding prudent, and began to beware of him.
1 Samuel 18:28-29
28 And Saul saw, and understood that the Lord was with David. And Michol the daughter of Saul loved him. 29 And Saul began to fear David more: and Saul became David’s enemy continually.
Catholic view (generated):
Saul wanted to kill David because he grew jealous of David's military successes and popularity among the people, seeing him as a threat to his own reign as king. This jealousy was fueled by the fact that Saul had lost favor with God, while David was favored by God. Ultimately, Saul's desire to kill David was driven by his own insecurity and fear of losing power.