In verse 19, Paul continues the line of thought about humans being restored to reign over a righteous and harmonious earth:For the anxious longing of the creation waits eagerly for the revealing of the sons of God. This refers to those who receive the reward of being adopted as a son. The creation is now in the futility of the fall; it was designed to be lovingly stewarded by faithful and serving humans. But that isn't happening now. But the creation waits eagerly for humans to be restored to manage it. That will be led by Jesus Christ, who had all authority given to Him for His faithful obedience (Matthew 28:18; Philippians 2:8-10). And Jesus will lead "many sons to glory" in restoring them to their rightful position (Hebrews 2:10). It is the restoration of these sons of God that the creation longs for, as they will share the inheritance of Christ (Romans 8:17b).
In speaking of sons of God, Paul is likely referring to a custom his Roman audience would have been familiar with as a coming-of-age ceremony for Roman males to progress from boy to man. There were two stages of Roman adoption (from boy to man):
1) to be placed as a "son" at age 14, with voting rights;
2) to be placed as a mature son at age 25, with property rights.
The analogy applies to believers in that all believers have "voting" rights now (free to choose sin or righteousness, Romans 6:16-19); but those who suffer with Christ will have "property rights" in the world to come (inheritance in His Kingdom, Romans 8:17b).
This can be confusing because as children born of the Spirit, we are born into God's family as children, and we tend to think of that as the only sort of adoption. But Paul uses the term both to describe becoming God's child (which comes with unconditional benefits all believers enjoy) as well as gaining a reward as a mature believer that is conditioned on faithfulness.
This idea of adoption for adults as a means of reward was not limited to Roman culture. In Hebrews 1, there is a rather elaborate description of Jesus being adopted as a "Son" over all humanity, largely quoted from Psalms. This is patterned after a common practice for eastern rulers to "adopt" a faithful servant into the royal family as a reward for faithful service, and bestow upon them property rights, territories over which to reign.
All believers are God's children, but only the believers who suffer with Jesus receive the reward of the inheritance that comes with Jesus's authority over the New Earth.
Right now, the creationwas subjected tofutility, not willingly, butbecause of Him who subjected it,in hopethatthe creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God (vv 20-21).
All of God's creation is agonizing and waiting for a restoration: For we know that the whole creation groans and suffers the pains of childbirth together until now (v 22). The hope remains that one day all of creation will be overseen by servant kings who serve in harmony and create harmony. The creation is in angst, and can't wait for that day to come.
The Him in verse 20 is referring to God, who cursed creation along with man, after Adam brought sin into the world (Genesis 3:17-19). Paul discusses the hope that creation has, along with believers, of redemption from God.
For creation, this redemption looks like re-creation, when God will make the new heavens and New Earth (Revelation 21:1). This "new creation" is the same sort of language referencing rebirth, renewal, and so forth that is used when Paul talks about believers as new creations (2 Corinthians 5:17, Galatians 6:15, Romans 6:4).
So, just as we long to be given new bodies and the glory that is to be revealed to us (v 18), so does creation. It longs for the redemption and re-creation in the new heavens and New Earth. Creation will be set free from its slavery to corruption when it is created anew, as Revelation 21 promises. We too will be made anew when we are freed from our mortal bodies and sin nature (v 10), and given new bodies, which Paul talks about in the next verse (23).
When we, as believers, are received into heaven (1 Thessalonians 4:16-18) we will be with the Lord forever, but heaven is not the final destination of believers; our final destination is a new earth (Revelation 21:1). We can think of heaven as a train stop on the way to our true destination, the New Earth (Revelation 21:1).
God's original design, which we find in Genesis chapters 1-3, was for man to rule over a perfect world in harmony with God, nature, and one another. But man and the earth/creation were cursed when Adam brought sin into the world. Our redemption through faith in Jesus is how God offers to restore us—and all of creation—to that original plan, serving with Jesus ruling over earth (Philippians 2:8-11).
(This inheritance of Jesus for His sacrifice on the cross and the opportunity we have to be fellow heirs with Him, is further explained in the commentary for verses 15-18.)
So, just as creation was cursed alongside man, it will be redeemed with us (believers) through faith. The suffering of creation is described as the pangs of childbirth together until now. This indicates that the earth will go through convulsing cycles until there is a great pain at the end, then a new creation is born. This is verified by Revelation and Daniel, which predict that the time of the end of this age will be accompanied by enormous tribulation (Matthew 24:22). But at the end, Jesus will return, and thus will begin a process of rebirth for all of creation.
