All Saul cares about is killing David. He doesn’t care about worshiping God. He doesn’t care about hearing from God. He doesn’t want to follow God. Yet, he justifies his actions by using the Name of God.
Now it was told Saul that David had come to Keilah. And Saul said, “God has given him into my hand, for he has shut himself in by entering a town that has gates and bars.”
1 Samuel 23:7 ESV
When we take our own preconceived ideas into a relationship with God, we will change His truth to validate our own ideals. Because Saul wanted David dead, and David seemed to be trapped, Saul assumed that God had approved his maniacal ideal to murder David.
“He easily believed what he greedily desired, though his own experience had oft showed him how strangely God had delivered [David] out of his own hands, and what a singular care God had over [David].”
Matthew Poole
Common sense would tell Saul that God was on David’s side. But common sense had been abandoned by this point. Since Saul has become obsessed with his own desires instead of God Himself, he has lost all spiritual discernment. It is a sad case study in how a corrupted attitude can blind us from God’s Spirit.
“It seems impossible that Saul could either have misunderstood or forgotten the word of the Lord delivered to him by Samuel; and yet he here speaks as though his pursuit of David was undertaken with the Divine approval, and puts an entirely false meaning upon his present position.”
Preacher’s Homiletic Commentary