Paul had last begun a discussion on the believers' adoption and the glory that would one day be revealed in them. Paul continued with this.
Romans 8:19-23 (KJV)
For the earnest expectation of the creature waiteth for the manifestation of the sons of God.
For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,
Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.
For we know that the whole creation groaneth and travaileth in pain together until now.
And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body.
In verse 19 Paul stated that creation is earnestly waiting for the manifestation (revealing) of the sons of God. This manifestation will take place as believers receive their glorified bodies. The human fleshly, corruptible body will no longer exist, but will be replaced by the glorified resurrected body that is no longer subject to decay.
Paul's statement indicates that creation itself is in a condition of decay and is seeking a release. According to verse 20, creation's condition resulted not from anything that it did, but was subjected or cursed because God desired it. Verse 21 finishes the explanation as to why God would curse creation. It was to create hope, that with the glorification of the children of God (believers), creation would also be set free from its slavery to corruption and would realize the same glorious liberty as the children of God.
Verse 22 further illustrates that creation is groaning and suffering as if it were experiencing the pains of childbirth. Notice that Paul used the word, "now." Although creation is still groaning, something occurred and made a change.
Verse 23 alludes to the change. Creation, as well as believers, have the firstfruits of the Spirit. Prior to the death and resurrection of Yeshua and the coming of the Holy Spirit creation could only groan under the burden of corruption. But since then creation and believers have an installment that gives hope for the final adoption or redemption of the body that will take place at the end of the age when Yeshua returns.
Ephesians 1:14 (KJV)
Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.
Although we can be saved spiritually now, the final redemption of the body is something that we have to look forward to. Creation joins us in that glorious hope for the future. What a glorious day that will truly be!