JCP: In practically every letter, Paul says he is called to be the apostle to the Gentiles. In fact he points out in the Galatian letter, that he, Paul, was entrusted with the gospel for the uncircumcised (Gentiles), as Peter was entrusted with the gospel for the circumcised (Jewish believers).
You asked, "Was he the only apostle?" The answer, "no". There were the 12 in Jerusalem; then, besides Paul, there was Silvanus and Timothy (1 Thes. 2:6); Barnabas (Acts 14:14 and 1 Cor. 9:3-6); Andronicus and
Junias (Rom.16:7); and Apollos (1 Cor.4:6-9).
Do OT doctrines apply to the Church today? My
answer is NO. They lived under the covenant of "I will bless you if you keep the law", etc. Animal sacrifices were part of their doctrine. A priest-hood and a temple (before it was destroyed). Keeping the Sabbath. Which meant no work, only a short distance to walk, etc. And, if two or more witnesses said you broke the Sabbath, the judgement was death.
Now, I want to say, that there are principals
true in every age, from Adam on. Such as faith, love, forgiveness, obedience, right living etc.
We, believers and members of the church/body of Christ are not children of Abraham according to the flesh. We, who are justified by faith as Abraham was justifed by faith, are his "children", because we follow his example of living by faith.
As to the future of the church/body being in the heavenlies, this is revealed in Ephesians
Quoting from the Concordant NT: 1:3 "Blessed be the God and Father of our Lord Jesus Christ, Who blesses us with every spiritual blessing among the celestials, in Christ, according as He chooses us in Him before the disruption of the world, we to be holy and flawless in His sight, in love designating us beforehand for the place of a son for Him through Christ Jesus; in accord with the delight of His will, for the laud of the glory of His grace, which graces us in the Beloved:"
God sees us as sons, perfect in the celestials through Christ. To enjoy spiritual blessings beyond our wildest imaginations. All because of God's grace.
In 2:4-6 it says, "God, being rich in mercy, because of His vast love with which He loves us(we also being dead to the offenses and lusts), vivifies us together in Christ (in grace are you saved!) and rouses us together and seats us together among the celestials, in Christ Jesus, that, in the oncoming eons, He should be displaying the transcendent riches of His grace in His kindness to us in Christ Jesus.
God, who sees the future as today, sees us, the believers, as being made alive and roused together with Christ, seated in the celestials.
Are you equating "resurrection" with "born again"? Paul, in 1 Cor.15, reveals a secret: not all in the body of Christ will die; but those who are alive when Christ gives the shout of command, and the trumpet blows, will put on immortality and, with those who are resurrected (those asleep in Christ), will meet the Lord in the air. And, since we know that, potentially, we will be seated in the heavenlies with Christ, then, that is where Christ takes us.
Well, JCP, I'll admit, there are many interpretaions. One book that I would recommend getting is "God's Eonian Purpose" by Adlai Loudy. It can be purchased over the web, as well as other publications, at www.concordance.org.
If you would want to discuss this more privately, we could correspond by email.
Let me know. Arnold