The believing remnant did not have to be re-saved through Paul's ministry.
Nobody ever said that. You are grasping at straws!
When Israel was set aside temporarily then the Jewish believers were made members of the Body of Christ and at that time they too had a heavenly calling just like all of the members of the Body of Christ. Here we see two different passages from the Scriptures which speak of a " heavenly calling":
"Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus" (Eph.2:5-6).
"But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel" (Heb.12:22-24).
Only those in the Body of Christ have a heavenly calling so those who received the Hebrew epistles were members of the Body of Christ.
This is not difficult to understand if you will just let the Scriptures be your guide.