What is the adoption believers are waiting for in verse 23?
The adoption believers await is the redemption of the body—not the soul or spirit, which are already redeemed. Paul explains in verse 23 that although believers have the firstfruits of the Spirit, they still groan inwardly, waiting for their corruptible body to become incorruptible when they enter the Lord’s presence.
Les explains that Romans 8:23 speaks of believers who have the firstfruits of the Spirit and still groan within themselves, waiting for the adoption, that is, the redemption of the body. The redemption of the soul and spirit is already concluded, but the body remains unredeemed. Paul says in 1 Corinthians 15 that this body is corruptible, and it will suddenly become incorruptible when believers go up into the presence of the Lord, receive their reward, and then come back as active participants in the kingdom. Les also notes that believers are already members of the heavenly kingdom, which will one day come to earth.
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.