Believing in Jesus is a work of God, not a choice of man.
Abraham had a God-initiated experience of hearing from God, just like Paul, that produced his faith. This experience of faith was credited to him as righteousness. So-called human “free will” to accept or reject what he heard was not part of the equation, and it is never part of the equation, just as human “free will” to accept or reject being born a sinner was never part of the equation.
“As in Adam all die” with no choice involved, “so in Christ all are made alive” with no choice involved. (Italicized text is mine.) 1 Corinthians 15:22
Just as there was no “free-will” choice in dying in Adam, there is no “free-will” choice involved in being made alive in Christ.
It is because of Him that you are in Christ Jesus, who has become for us wisdom from God—that is, our righteousness, holiness, and redemption. Therefore, as it is written, “Let him who boasts, boast in the Lord.” 1 Corinthians 1:30-31
Translation: Believing in Jesus is a work of God, not a choice of man.