Saul lost his salvation,

Then Saul said to Samuel, "I have sinned; I have indeed transgressed the command of the LORD ... As Samuel turned to go, Saul seized the edge of his robe, and it tore. ²⁸ So Samuel said to him, "The LORD has torn the kingdom of Israel from you today and has given it to your neighbor, who is better than you. ²⁹ .... ³⁰Then he (Saul)  said, "I have sinned; but please honor me now before the elders of my people and before Israel, and go back with me, that I may worship the LORD your God." ³¹ So Samuel went back following Saul, and Saul worshiped the LORD.

Surely there was no one like Ahab who sold himself to do evil in the sight of the LORD, because Jezebel his wife incited him.  He acted very abominably in following idols, according to all that the Amorites had done, whom the LORD cast out before the sons of Israel.  It came about when Ahab heard these words, that he tore his clothes and put on sackcloth and fasted, and he lay in sackcloth and went about despondently. ²⁸Then the word of the LORD came to Elijah the Tishbite, saying, ²⁹ "Do you see how Ahab has humbled himself before Me? Because he has humbled himself before Me, I will not bring the evil in his days, but I will bring the evil upon his house in his son's days."

For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit, ⁵ and have tasted the good word of God and the powers of the age to come, ⁶ and then have fallen away, it is impossible to renew them again to repentance .....

I believe everything the bible says. Don't you?

My sheep hear My voice, and I know them, and they follow Me;  and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand.  "My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father's hand.