
The Book of Romans in Chapter 8 verses 15-30 and 35, speaks of the “children of God”:
15 Because the Spirit that God has given to you does not make you like slaves again. He does not make you slaves who cannot stop being afraid. Instead, the Spirit that God has given to you causes you to become God’s children. He makes us able to shout to God: ‘You are my Father.’
16 God’s Spirit himself causes us to know certainly what we know by our own spirits. We know that we are God’s children.
17 And because we are God’s children, we will also receive good things from him. We will receive the things that God has prepared for his children. Also, together with Christ, we will receive the things that God has kept for him. We will receive these things if we agree to have troubles and pain, as Christ did. So then, as a result, we will also live always with God, who is so great and so good.
18 During this time now, we have troubles and pain. But I am sure that these troubles are not really very important. They are not really important because God has prepared much, much better things for us. He is keeping these great and good things for us. And when we think about these great things, our troubles now do not seem important.
19 All things that God has made are waiting for a future time. They want that time to come very much. At that time, God will show them who his sons really are.
20 God has caused the things that he made to become without real purpose. Those things are unable really to have any purpose. They did not choose to become like that. It was God who caused them to become like that. God did that because he was thinking about that future, better time.
21 At that time, God will also cause the things that he has made to become free. They will be free from the power that causes them to become old and to finish. They will be free to enjoy great things from God, as God’s children are free.
22 All the things that God has made have been waiting until now. We know that. They have been waiting like a woman who is ready to have a baby. She cries because of her pain before she has her baby.
23 And it is not only those other things in the world that are waiting like that. But we ourselves, who have received God’s Spirit as the first of his gifts to us, are also crying. We are crying deep inside ourselves, while we wait for God to finish making us his own children. We are waiting for God to make our bodies free.
24 Ever since God saved us, we have continued to hope certainly for this. One day, we will see what we have hoped for. And then we will not need to hope for it any more. Nobody continues to hope for something that he has already.
25 But we continue to hope for what we do not have yet. And so, we wait for it patiently.
26 God’s Spirit also helps us, because we are weak. We do not know how we ought to pray. But God’s Spirit himself prays on our behalf. He cries to God on our behalf in a way that nobody could say with words.
27 And God, who sees deep inside us, understands the Spirit. God sees completely what we are really like. And he understands what his Spirit is thinking. The Spirit prays on behalf of God’s people as God wants him to pray.
28 God has good purposes for those people who love him. We know that. He uses everything that happens to them to bring good results on their behalf. He does this for those people that he has chosen. He has chosen his people to be what he wants them to be.
29 God had already chosen those people from the beginning. And he had decided that they should become like his Son. So then, as a result, his Son would be the first among many brothers.
30 God decided that those people would be like his Son. Also, he asked them to come to him. And after he had asked them to come to him, he made them right with himself. And when he had made them right with himself, he also caused them to become great. He made them great and good, in the same way that he himself is great and good.
35 Nothing can make us separate from Christ, who loves us. We may have troubles. Things may happen to us that cause us to be very sad or afraid. Enemies may do bad things to us and hurt us. We may have no food or no clothes. There may be danger, or people may try to kill us. But none of these things can stop Christ from loving us.
Why is “all of creation” eagerly waiting for the “revealing of the sons of God”?
Verses 20-22 provides the answer for us;

“For the creation was subjected to futility, not willingly, but because of him who subjected it, in hope that the creation itself will be set free from its bondage to corruption and obtain the freedom of the glory of the children of God”. Romans 8:20,21
“For the creation was subjected to futility, not willingly, but because of Him who subjected it in hope; because the creation itself also will be delivered from the bondage of corruption into the glorious liberty of the children of God. For we know that the whole creation groans and labors with birth pangs together until now.”
This passage takes us back to the Garden of Eden and fall of man.
When Adam chose to listen to his wife instead of listening to God, he sinned and it affected all creation; even the Earth and the things upon it.
In judging Adam this is what God said to him:
Genesis 3:17-18:
To Adam he said, “Because you have listened to your wife’s voice, and have eaten of the tree, of which I commanded you, saying, ‘You shall not eat of it,’ cursed is the ground for your sake. In toil you will eat of it all the days of your life.
18 Thorns also and thistles will it bring forth to you; and you will eat the plants of the field”.
As we read through the Bible, we see that the animal kingdom suffered the same fate as well; the curse was stamped on the whole creation, bringing with it tribulation, disease, and ultimately death.
Because of this “the whole creation groans and labors with birth pangs together until now.” ESV
How and when will creation be set free of the curse God placed upon it due to original sin?
This brings us to verse 19 which tells us that creation will not be freed until, “the revealing of the sons of God.”
Who Are the “Sons of God”?
These “sons of God” are also the “children” and “heirs” mentioned in verses 16-17:
Romans 8:15-17:
15 For you did not receive a spirit that makes you a slave again to fear, but you received the Spirit of sonship. And by him we cry, “Abba, Father.”
16 The Spirit himself testifies with our spirit that we are God’s children.
17 Now if we are children, then we are heirs — heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory.
Compare with Jesus’ words at Luke 20:36:
“for they cannot die anymore, because they are equal to angels and are sons of God, being sons of the resurrection”.
These children are the joint heirs of Christ who will share a Heavenly existence with the Lord after their deaths and resurrection. They are biblically referred to as the “first fruit”.
Revelation 14:
1 And I looked, and, lo, a Lamb stood on the mount Zion, and with him and hundred forty and four thousand, having his Father’s name written in their foreheads.
2 And I heard a voice from heaven, as the voice of many waters, and as the voice of a great thunder: and I heard the voice of harpers harping with their harps:
3 And they sung as it were a new song before the throne, and before the four beasts, and the elders: and no man could learn that song but the hundred and forty and four thousand, which were redeemed from the earth.
4 These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men, being the first fruits unto God and to the Lamb.
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Note: Verse 4 above states, “These are they which were not defiled with women”. These words reflect back to the command God gave to Moses recorded in the Book of Exodus in Chapter 19 that Moses was to give as instruction to the people because they were about to perform a sacred service and would have to remain ritually clean as a priest is required to do.
Exodus 19:15
“And he said to the people, ‘Be ready for the third day; do not come near your wives.”’
Their “virginity” has to do with being ritually clean and does not suggest that they have to be unmarried and not having had sexual intercourse. The general idea is, that they are chaste and pure at heart; that they are the followers of the Lamb alone; and that they are without deception.
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If there are “first fruit” then it stands to reason that there is other fruit to be harvested. Not all believers are sharers in the Heavenly calling.
There are a specific number called to priestly service in Heaven as mentioned on Revelation 14: 1:
“And I looked, and, lo, a Lamb stood on the mount Zion, and with him and hundred forty and four thousand, having his father’s name written in their foreheads.”
They are called from the state of the dead in what the Bible terms the “first resurrection”.
Revelation 20:
4 And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
5 But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.
6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ,and shall reign with him a thousand years.
When the full number of them has been filled, then Jesus will come and gather them all to Heaven. This would include any living and those already sealed who lie asleep in death.
The “sons of God” will only be known after they have all been “sealed” because they must complete their life course faithfully. So, the apostle Paul counsels the church at Ephesians 4:30:
“And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption”.
It will be revealed at the Coming of the Lord, both to those in Heaven and all who witness on Earth who the son of God are.