Also, let's look at God's calling of Jeremiah the prophet:Jeremiah 1: 4-5: Then the word of the L ORD came to me, saying: " Before I formed you in the womb I knew you; Before you were born I sanctified you; I ordained you a prophet to the nations."
It does say that before Jeremiah was ever born, God knew him and God ordained him to be a prophet.
However, that says nothing about God ordaining Jeremiah's eternal salvation.
So God calls Jeremiah and touches his lips with the words of the LORD sets him apart, tells him He is with him, and your looking for proof of Jeremiahs salvation?
Saul
Notice, God had chosen others to act as prophets (such as King Saul), but they turned wicked and were not saved:
1st Samuel 10:9-13: So it was, when he had turned his back to go from Samuel, that God gave him another heart; and all those signs came to pass that day. When they came there to the hill, there was a group of prophets to meet him; then the Spirit of God came upon him, and he prophesied among them. And it happened, when all who knew him formerly saw that he indeed prophesied among the prophets, that the people said to one another, "What is this that has come upon the son of Kish? Is Saul also among the prophets?" Then a man from there answered and said, "But who is their father?" Therefore it became a proverb: "Is Saul also among the prophets?" And when he had finished prophesying, he went to the high place.
Because the Holy Spirit in the OT is used to enable people to do certain task that God wants, you turn that into someone rejecting Gods calling see Judges 3:6-10 and 2Chr 36 and Numbers 24
8 Then the anger of the LORD was kindled against Israel, so that He sold them into the hands of Cushan-rishathaim king of Mesopotamia and the sons of Israel served Cushan-rishathaim eight years. 9 When the sons of Israel cried to the LORD, the LORD raised up a deliverer for the sons of Israel to deliver them, Othniel the son of Kenaz, Caleb's younger brother. 10 The Spirit of the LORD came upon him, and he judged Israel. When he went out to war, the LORD gave Cushan-rishathaim king of Mesopotamia into his hand, so that he prevailed over Cushan-rishathaim
Look at 2Chronicles 36
14 Furthermore, all the officials of the priests and the people were very unfaithful {following} all the abominations of the nations; and they defiled the house of the LORD which He had sanctified in Jerusalem. 15 The LORD, the God of their fathers, sent { word} to them again and again by His messengers, because He had compassion on His people and on His dwelling place; 16 but they {continually} mocked the messengers of God, despised His words and scoffed at His prophets, until the wrath of the LORD arose against His people, until there was no remedy. 17 Therefore He brought up against them the king of the Chaldeans who slew their young men with the sword in the house of their sanctuary, and had no compassion on young man or virgin, old man or infirm; He gave {them} all into his hand. 18 All the articles of the house of God, great and small, and the treasures of the house of the LORD, and the treasures of the king and of his officers, he brought {them} all to Babylon. 19 Then they burned the house of God and broke down the wall of Jerusalem, and burned all its fortified buildings with fire and destroyed all its valuable articles.
Here in Numbers24 God uses a sorcerer;
1 When Balaam saw that it pleased the LORD to bless Israel, he did not go as at other times to seek omens but he set his face toward the wilderness. 2 And Balaam lifted up his eyes and saw Israel camping tribe by tribe; and the Spirit of God came upon him.
Did God save this sorcerer.
Point is God gets what he wants period!