For the earnest expectation -- [RSV, ESV eager longing; NASB anxious longing; NCV waiting with excitement; NIV eager expectation] -- ἀποκαραδοκία apokaradokia. This word occurs only here and in Philippians 1:20, “According to my earnest expectation and my hope,” etc. It properly denotes a state of earnest desire to see any object when the head is thrust forward; an intense anxiety; an ardent wish; and is thus well employed to denote the intense interest with which a Christian looks to his future inheritance. - BN
Earnest expectation—A single word in the Greek, and a very striking one. It means, literally, a straining forward with outstretched head, just as we might imagine the crowds outside a race-course straining over the ropes to catch a sight of the runners; an eager, intent expectation. The same word is used once again in the New Testament (Philippians 1:20). - Ellicott
of the creation -- τῆς κτίσεως tēs ktiseōs (cf "creation" in Romans 8:19-22.)
[Perhaps there is not a passage in the New Testament that has been deemed more difficult of interpretation than this Romans 8:19-23; and after all the labors bestowed on it by critics, still there is no explanation proposed which is perfectly satisfactory, - BN]
"Creature" is rendered creation in the Revision, and this rendering is approved by all the best critics. Chrysostom says "Paul personifies the world, just as the prophets do when they make the floods to clap their hands." The whole world is represented earnestly looking forward to that day of future glory when the sons of God will have reached their high estate and be revealed as his children. It is a fine, poetic figure, a grand conception. - PNT
The creature: this word is four times used in this and the three following verses, only in Romans 8:22 it is rendered creation; that is the subject of which all that followeth is predicated. One main question therefore is this: Of what creature the apostle here speaks? Divers answers are or may be given; I will fix upon two only.
1. By the creature, or the creation, ,{ and, Romans 8:22, the whole creation, or every creature} is meant all mankind, both Jews and Gentiles, and especially the latter: see Mark 16:15; there Christ gives it in commission to preach the gospel to every creature; it is the same word. And in 1 Peter 2:13, they are commanded to submit themselves to every ordinance of man: in the original it is, to every human creature, the same word which is in the text before us: he means the Gentile or heathen magistrates in authority over them. In the Scripture the Gentiles are sometimes called the world, Romans 11:12,15, and sometimes the creature, or the creation.
2. By the creature is meant the whole world with all the creatures therein, or the whole frame and body of the creation. - Poole
creation -- Barnes (after giving a number of various views) believes it to refer to the Christian (the renewed man with a renewed heart), as the new creation, regarded individually. [Such a view also seems "to suit the connection, and to make sense in the argument" will all the following verses. -WG]
creation -- This seems to me to simply be a reference to those mentioned in the previous verse [ημας ] "us" Romans 8:18, [and "we" in v. 23] and a further explanation of the glory which shall be revealed in this, that is, the redemption of their corruptible bodies. - WG [v. 22 The "whole creation" may here be a personification of God’s entire creation.]
It seems that most modern critics take this as "The physical creation is personified as a person with an outstretched neck searching the horizon. Creation was negatively affected when Adam and Eve rebelled (cf. Genesis 3:17-19). All creation will ultimately be redeemed (except for rebellious angels, unbelieving humans, and their prepared place of isolation" - Utley [Such a view seems to believe that "heaven" will be here on a re-newed earth. - WG]
eagerly waits -- Expects; is not in a state of possession, but is looking for it with interest.
for the revealing -- The ἀποκάλυψις (apokálupsis) "disclosure, unveiling, uncovering". The manifestation. The full development of the benefits of the sons of God; the time when they shall be acknowledged, and received into the full privileges of sons.
The revealing of the sons of God will occur when Christ returns for His own. They will share His glory (Romans 8:18; Colossians 1:27; Colossians 3:4; Hebrews 2:10), and will be transformed (Romans 8:23). All of nature (inanimate and animate) is personified as waiting eagerly for that time. - BKC
of the sons of God -- The real children of God, John_8 not sons of flesh but sons of faith.