There is but one Greek word beside aiónios rendered everlasting, and applied to punishment, in the New Testament, and that is the word aidios found in Jude 6: "And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgement of the great day." This word is found in but one other place in the New Testament, viz. Rom. i:20: "For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead."
Now it is admitted that this word among the Greeks had the sense of eternal, and should be understood as having that meaning wherever found, unless by express limitation it is shorn of its proper meaning. It is further admitted that had aidios occurred where aiónios does, there would be no escape from the conclusion that the New Testament teaches Endless Punishment. It is further admitted that the word is here used in the exact sense of aiónios, as is seen in the succeeding verse: "Even as Sodom and Gomorrah, and the cities about them in like manner, giving themselves over to fornication, and going after strange flesh, are set forth for an example, suffering the vengeance of eternal fire." That is to say, the "aidios" chains in verse 6 are "even as" durable as the aiónion fire" in verse 7. Which word modifies the other?
1. The construction of the language shows that the latter word limits the former. The aidios chains are even as the aiónion fire. As if one should say "I have been infinitely troubled, I have been vexed for an hour," or "He is an endless talker, he can talk five hours on a stretch." Now while "infinitely" and "endless" convey the sense of unlimited, they are both limited by what follows, as aidios, eternal, is limited by aiónios, indefinitely long.
2. That this is the correct exegesis is evident from still another limitation of the word. "The angels - - - he hath reserved in everlasting chains UNTO the judgement of the great day." Had Jude said that the angels are held in aidios chains, and stopped there, not limiting the word, we should not dare deny that he taught their eternal imprisonment. But when he limits the duration by aiónion and then expressly states that it is only unto a certain date, we understand that the imprisonment will terminate, even though we find applied to it a word that intrinsically signifies eternal duration, and that was used by the Greeks to convey the idea of eternity, and was attached to punishment by the Greek Jews of our Savior's times, to describe endless punishment, in which they were believers.
But observe, while this word aidios was in universal use among the Greek Jews of our Savior's day, to convey the idea of eternal duration, and was used by them to teach endless punishment, he never allowed himself to use it in connection with punishment, nor did any of his disciples but one, and he but once, and then carefully and expressly limited its meaning. Can demonstration go further than this to show that Jesus carefully avoided the phraseology by which his contemporaries described the doctrine of endless punishment? He never employed it. What ground then is there for saying that he adopted the language of his day on this subject? Their language was aidios timoria, endless torment. His language was aionion kolasin, age-lasting correction. They described unending ruin, he discipline, resulting in reformation. - end quote
Let me quote something briefly from a scholarly work by Thomas Allin, entitled "Christ Triumphant":
"Let me state the dilemma clearly. Aion either means endless duration (in Scriptural usage) as its necessary, or at least it's ordinary significance, or it does not. If it does, the following difficulties at once arise; 1 - How if it means an endless period can aion have a plural? 2 - How came such phrases to be used as those repeatedly occuring in Scripture, where aion is added to aion, if aion is of itself infinite? 3 - How come such phrases as for the "aion" or aions and beyond? - ton aiona kai ep aiona kai eti: eis tous aionas kai eti. - See (Sept.) Ex. xv. 18; Dan xii. 3; Micah iv. 5. 4 - How is it that we repeatedly read of the end of the aion? - S. Matt. xiii. 39-40-49; xxiv. 3; xxviii. 20; 1Cor. x. 11; Heb. ix. 26. 5 - Finally, if aion be infinite, why is it applied over and over to what is strictly finite? e.g., S. Mark iv. 19; Acts iii. 21; Rom. xii. 2; 1Cor. i. 20, ii. 6, iii. 18, x. 11, &c., &c. But if an aion be not infinite, what right have we to render the adjective aionios (which depends on it's meaning on aion) by the terms "eternal" (when used as the equivalent of "endless") and "everlasting?" Indeed our translators have really done further hurt to those who can only read their English Bible. They have, wholly obscured a very important doctrine, that of "the ages." This when fully understood throws a flood of light on the plan of redemption, and the method of the divine working." - end quote.
Ancient writings, other than the Scriptures, show how aion and aionios were used in the ordinary affairs of that time period. Long ago in Rome, periodic games were held. These were referred to as "secular" games. Herodian, who wrote in Greek about the end of the second century A.D., called these aionios, "eonian," games. In no sense could those games have been eternal.
In 1Enoch 10:10 there is an interesting statement using the Greek words: zoên aionion, "life eonian," or, as in the KJV, "everlasting life" (at John 3:16 and elswhere). The whole sentence in Enoch is, hoti elpizousi zêsai zoên aionion, kai hoti zêsetai hekastos auton etê pentakosia, "For they hope to live an eonian life, and that each one of them will live five hundred years." Here, eonian life is limited to five hundred years!
St. Justin Martyr repeatedly used the word aionios as in the Apol. (p. 57), aionion kolasin ...all ouchi chiliontaetê periodon, "eonian chastening ...but a period, not a thousand years." Or, as some translate the last clause: "but a period of a thousand years only." He limits the eonian chastening to a period of a thousand years, rather than to endlessness.
Josephus shows that aionios did not mean endlessness, for he uses it of the period between the giving of the law to Moses and that of his own writing; to the period of the imprisonment of the tyrant John by the Romans; and to the period during which Herod's temple stood. The temple had already been destroyed by the time Josephus was writing.
Dr. Mangey, a translator of the writings of Philo, says Philo did not use aionios to express endless duration.
Adolph Deissman gives this account: "Upon a lead tablet found in the Necropolis at Adrumetum in the Roman province of Africa, near Carthage, the following inscription, belonging to the early third century, is scratched in Greek: 'I am adjuring Thee, the great God, the eonian, and more than eonian (epaionion) and almighty...' If by eonian, endless time were meant, then what could be more than endless time?"
In the Apostolical Constitutions, a work of the fourth century A.D., it is said, kai touto humin esto nomimon aionion hos tes suntleias to aionos, "And let this be to you an eonian ordinance until the consummation of the eon." Obviously there was no thought in the author's mind of endless time.
In the Iliad and Odyssey Aión occurs thirteen times, as a noun, besides its occurrence as a participle in the sense of hearing, perceiving, understanding. Homer never uses it as signifying eternal duration. Priam to Hector says, "Thyself shall be deprived of pleasant aiónos" (life.) Andromache over dead Hector, "Husband thou hast perished from aiónos" (life or time.)
Pindar gives thirteen instances, such as "A long life produces the four virtues."(Ela de kai tessaras aretas ho makros aión.)
Sophocles nine times. "Endeavor to remain the same in mind as long as you live." Askei toiaute noun di aiónos menein. He also employs makraion five times, as long-enduring. The word long increases the force of aión, which would be impossible if it had the idea of eternity.
Hippocrates. "A human aión is a seven days matter."
Empedocles, An earthly body deprived of happy life, (aiónos.)
Euripides uses the word thirty-two times. I'll quote three instances: "Marriage to those mortals who are well situated is a happy aión." "Every aión of mortals is unstable." "A long aión has many things to say," etc.
From Andrew Jukes's "Restitution of all things" we read:
Every scholar knows that the expressions, "ages," "to the ages," "age of the ages," and "ages of the ages," are unlike anything which occurs in the heathen Greek writers. The reason is, that the inspired writers, and they alone, understood the mystery and purpose of the "ages." They, or at least the Spirit which spake by them, saw that there would be a succession of "ages," a certain number of which constituted another greater "age." It seems to me that when they simply intended a duration of many "ages," they wrote "to the ages." When they had in view a greater and more comprehensive "age," including in it many other subordinate "ages," they wrote "to the age of ages." When they intended the longer "age" alone, without regard to its constituent parts, they wrote "to an aeonial age"; this form of expression being a Hebraism, exactly equivalent to "age of the ages:" like "liberty of glory," for "glorious liberty," (Rom. viii. 21,) and "body of our vileness," for "our vile body." (Phil. iii. 21.) When they intended the several comprehensive "ages" collectively, they wrote "to the ages of ages." Each varying form is used with a distinct purpose and meaning. - end of quote.
And with regards to specific promises of the Regeneration of all things in the Scriptures that aren't translational issues:
The Scriptures are clear that Jesus Christ is the Savior of the world, and is the atoning sacrifice for our sins and for those of the world. To bring this out clearly, I append the following chain of passages from a long series, clearly and closely linked together, claiming for Christ a saving empire co-extensive with the whole universe. The connection is clearly marked, for each passage suggests or contains, the same central idea; and thus forms a link in a continuous chain. This chain commences at Creation, when all things were created by Christ, Who, therefore, as St. Paul implies, reconciles(in fact, recreates) all things unto God(Colossians 1:15-20). Hence His work is the restitution of all things(Acts 3:21); He is Heir of all things(Hebrews 1:2); in Him all nations are to be blessed(Galatians 3:8); for the Father has given Him authority over all flesh, to give to whatsoever was given to Him eternal life(John 17:2); and so all flesh shall see the salvation of God(Luke 3:6). For God, Whose counsel is immutable(Hebrews 6:17), Whose attitude towards His enemies is love unchanging(Luke 6:27-35), will have all men to be saved(ITimothy 2:4); and all to come to repentance(2 Peter 3:9); and has shut all up unto unbelief, in order that he may shew mercy upon all(Romans 11:32); for (out) of Him, as Source, and unto (or into) Him, as End, are all things whatsoever(Romans 11:36); and He has, therefore, put all things into subjection under Christ's feet(Ephesians 1:22). And so we are assured that God will gather into one all things in Christ(Ephesians 1:10); and His grace comes upon all men unto justification of life(Romans 5:18). So Jesus, knowing that the Father had given all things into His hands(John 13:3), promises by His Cross to draw all men unto Himself(John 12:32). For having, as stated, received all things from the Father(John 3:35), all that was given come to Him; and He loses none(John 6:37-39); but if any stray, goes after that which is lost till He find it(Luke 15:4); and so makes all things new(Revelation 21:5). And thus He comes in order that all men may believe(John 1:17); that the world, through Him, may be saved(John 3:17); His grace brings salvation to all men(Titus 2:11); for He takes away the sin of the world(John 1:29); gives His flesh for it's life(John 6:51); and, because the gifts and calling of God are without repentance(Romans 9:29), He gives life to the world(John 6:33); is the light of the world(John 8:12); is the propitiation for the sins of the whole world(1John 2:2); is the Savior of all men(1Timothy 4:10); destroys the works of the devil, not some of them only(1John 3:8); abolishes death(2Timothy 1:10); is manifest to put away sin(Hebrews 9:26); and thus subduing all things unto Himself(Philippians 3:21; the context clearly shows this subjection to be conformity to Himself); does not forget the dead, but takes the gospel to Hades(1Peter 3:19); of which He holds the keys(Revelation 1:18); for He is the same (Savior) for ever(Hebrews 13:8); thus even the dead are evangelized(1Peter 4:6); Thus all are made alive in Him(1Corinthians 15:22); for Christ finishes, completes His work(John 17:4; 19:30): restores all things(Acts 3:21); and there is no more curse(Revelation 22:2-3); but every knee of things in heaven and earth, and under the earth, bends to Him(Philippians 2:10); for the creation is delivered from the bondage of corruption(Romans 8:21); and every creature joins in the song of praise(Revelation 5:13), and so comes the end when Christ delivers up the Kingdom to God, Who is then All in All(1Corinthians 15:24-28).