God doesn’t “unsave” them. They leave the faith. They were in the faith and then elected to leave it. In the early days of the church, many times they returned to Judaism.
In 1 Cor, Paul orders the church to turn a sinner “over to Satan for the destruction of his flesh” so that his spirit might be Saved.
Judas walked with Jesus as a Disciple and still fell. The idea that Jesus chose him in order to see to his ultimate destruction sounds disingenuous.
Free Will means that we can leave or stay.
There's where we disagree. I believe God alone dictates salvation by whatever criteria his good will chooses. "I will have mercy on who I choose to have mercy" We'll just have to agree to disagree on this.