For the anxious longing of the creation waits eagerly for the revealing of the sons of God.
This verse, and the surrounding verses, speak of our glorification—that is, the revealing, or the glorification of the sons of God (all believers in Christ).
Now the question before us is, when will this happen? And also, how will it happen? Verses 19 through 25 indicates that we are waiting eagerly for it to happen.
For the anxious longing of the creation waits eagerly for the revealing of the sons of God. 20 For the creation was subjected to futility, not of its own will, but because of Him who subjected it, in hope 21 that the creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God. 22 For we know that the whole creation groans and suffers the pains of childbirth together until now. 23 And not only this, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body. 24 For in hope we have been saved, but hope that is seen is not hope; for why does one also hope for what he sees? 25 But if we hope for what we do not see, with perseverance we wait eagerly for it. (Bold for emphasis)
But to really understand how our glorification transpires, I think we should look at another verse—1 John 3:2. Here, though we don’t have the word “reveal” in the text, as in Romans 8:18-19, we have the same idea; and here it explains the glorification process.
The verse reads,
“Beloved, now we are children of God, and it has not appeared as yet what we shall be. We know that, when He appears, we shall be like Him, because we shall see Him just as He is.”
Therefore, what it is saying is that when He comes and is revealed to us and we see Him as He is, in that moment we will be instantly glorified as He is.
This sounds like the rapture doesn’t it? It sounds something like 1 Corinthians 15:51-52:
“Behold, I tell you a mystery; we shall not all sleep, but we shall all be changed, 52 in a moment, in the twinkling of an eye, at the last trumpet; for the trumpet will sound, and the dead will be raised imperishable, and we shall be changed.”
And this change, or this instant glorification happens as He catches us up with Him and takes us to heaven. 1 Thessalonians 4:16-17 says,
For the Lord Himself will descend from heaven with a shout, with the voice of the archangel, and with the trumpet of God; and the dead in Christ shall rise first. 17 Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air, and thus we shall always be with the Lord.
What is described here, the rapture of the church, is what I believe is the meaning of “the revealing of the sons of God.” Thus we are eagerly waiting for the time when our bodies are redeemed (v. 23) and are glorified like His. So, we could say that we are waiting for Him to come to us, so that He will glorify us like Himself. (And also, we must note from this passage that the whole creation is waiting to be restored to its original purpose and beauty, which will happen in the millennium.)
There is much more we could say about this idea of eagerly waiting for His return to rapture us to heaven (vv. Rom. 8:19; 23, 25). For many, this idea of waiting has made the rapture quite unpopular, because they say that such weak believers are only seeking (waiting) to escape their Christian responsibilities. Well, I strongly disagree with that, for the bible tells us in many places that if we fix our hope upon the return of Christ, this (fixing and eagerly waiting) will result in our godliness in this present life (e.g. 1 Pet. 1:1-13; 1 Jn. 3:3).