What is resurrected in heaven? When a man dies, the body decayes in the grave, but what about the spirit of man? Ecc 12:7 And the dust returns to the earth as it was, and the spirit returns to God who gave it.
Ecc 3:20 All go to one place. All are from the dust, and all turn to dust again. – People and animals all die and return to the dust of the earth. Ecc tells how the “dust” i.e the human body returns to earth, but the spirit rises to God in heaven.
Stefanus knew the same thing when he said just before his death: Act 7:59: As they continued to stone Stephen, he kept praying, Lord Jesus, receive my spirit! – Stefanus did not speak anything about the soul! The spirit, in Greek pneuma πνεῦμα, is going up to heaven but not the soul. Did not Stephen, therefore, believe that he had an immortal soul which he would like to end up in heaven? A soul, i.e a human being or a living creature, decays in the grave, but the spirit of man is with God in heaven ready for resurrection.
Heb 12 speaks of a kingdom which cannot be shaken (v. 28) and the church of the firstborn and the spirits of the righteous made perfect. The spirit of man (pneuma) is the word used by the Greeks to describe God’s human spirit. In his spirit, man can experience the encounter with God. When apostle Paul wishes at the end of the Galatians to bless the congregation of Galatia as a brother in Christ, he says: Gal 6:18 The grace of our Lord Jesus Christ be with your spirit, brothers. Amen. Also Phl 4:23 May the grace of the Lord Jesus Christ be with your spirit! Amen.
In his letter to the Romans, Paul conveys a promise: Rom 8:11 But if the Spirit of him who raised up Jesus from the dead dwells in you, he who raised up Christ Jesus from the dead will also give life to your mortal bodies through his Spirit who dwells in you.
There are also other non-righteous spirits who do not inherit the kingdom. They are described in Eph 2:2: in which you once walked according to the course of this world, according to the prince of the powers of the air, the spirit who now works in the children of disobedience;
In the first resurrection, the saints in the spirit body will inherit the kingdom of Heaven (or God) and Christ is their king: Heb 12:28 Therefore, since we are receiving a kingdom that cannot be shaken, let us be thankful and worship God in reverence and fear in a way that pleases him.
The Spirit himself testifies with our spirit that we are children of God; and if children, then heirs; heirs of God, and joint-heirs with Christ; if indeed we suffer with him, that we may also be glorified with him. (Rom 8:16-17)