Is that a fact?
In the following twenty three [23] verses αἰών/aion and αἰώνιος/aionios are defined/described, by comparison or contrast with other adjectives or adjectival phrases, as eternal, everlasting etc.:
1 Timothy 1:17, 2 Corinthians 4:17-18, 2 Corinthians 5:1, Hebrews 7:24, 1 Peter 1:23, 1 Timothy 6:16, Galatians 6:8, John 6:58, John 10:20, 1 John 2:17, 1 Peter 5:10, Romans 2:7, Luke 1:33, Revelation 14:11, John 10:28, John 3:15, John 3:16, John 5:24, John 8:51, Ephesians 3:21, Romans 1:20, Romans 5:21, Romans 16:26.
…..In the NT “aion/aionios” refer to things which are not eternal but neither word is ever defined/described, by other adjectives or adjectival phrases, as meaning a period of time less than eternal, as in the following verses.
[1]Romans 1:20
(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 [ἀΐ́διος/aidios] power and Godhead; so that they are without excuse:
[2]Romans 16:26
(26) But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting [αἰώνιος/aionios] God, made known to all nations for the obedience of faith:
In Romans 1:20 Paul refers to God’s power and Godhead as “aidios.” Scholars agree “aidios” unquestionably means eternal, everlasting, unending etc. In Rom 16:26, Paul, the same writer, in the same writing, refers to God as “aionios.” Paul has used “aidios” synonymous with “aionios.” In this verse by definition “aionios” means eternal, everlasting.
[3]Luke 1:33
(33) And he shall reign [βασιλευσει][Vb] over the house of Jacob for ever; [αιωνας/aionas] and of his kingdom [βασιλειας][Nn] there shall be no end.[τελος/τελος]
In this verse the reign βασιλευσει/basileusei, which is the verb form of the word, is "aionas" and of the kingdom βασιλειας/basileias, the noun form of the same word, "there shall be no end.” “Aionas” by definition here means eternal.
[4]2 Corinthians 4:17-18
(17) For our light affliction, which is but for a moment, worketh for us a far more exceeding and eternal [αἰώνιος/aionios] weight of glory;
(18) While we look not at the things which are seen, but at the things which are not seen: for the things which are seen are temporal;[πρόσκαιρος/proskairos] but the things which are not seen are eternal [αἰώνιος/aionios]
In this passage “aionios” is contrasted with “for a moment,” vs. 4, and “temporal,” vs. 5. “Age(s)” a indeterminate finite period, it is not the opposite of “for a moment”/”temporal/temporary” “eternal” is. “Aionios” by definition here means “eternal.”
[5]2 Corinthians 5:1
(1) For we know that if our earthly house of this tabernacle were dissolved, we have a building of God, an house not made with hands, eternal [αἰώνιος/aionios] in the heavens.
In this verse “aionios house” is contrasted with “earthly house which is destroyed.” Is God going to replace our destroyed earthly house with an ages long house which will also be destroyed at the end of an age? The aionios house is not destroyed, the opposite of “is destroyed.” Thus “aionios” by definition here means “eternal.”
[6]Hebrews 7:24 but because Jesus lives forever [αἰών/aion] he has an unchangeable [ἀπαράβατος/aparabatos] priesthood.
In this verse “aion” is paired with “unchangeable.” If “aion” means “age(s),” Jesus cannot continue “for a finite period” and be “unchangeable” at the same time. Thus “aion” by definition here means “eternal.”
[7]1 Peter 1:23
(23) For you have been born again, not of perishable seed, but of imperishable, [ ̓́αφθαρτος/aphthartos] through the living and enduring word of God. …
1 Peter 1:25
(25) but the word of the Lord endures forever.[αἰών/aion] " And this is the word that was preached to you.
In verse 23 “word of God” is paired with “imperishable.” In verse 25 the word of God “endures εις τον αιωνα unto eternity. ” Thus by definition “aion” here means “eternity.”
[8]1 Timothy 6:16
(16) Who only hath immortality, [ ̓́αφθαρτος/aphthartos] dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom be honour and power everlasting [αἰώνιος/aionios]
In this verse “aionios” is paired with “immortality.” If “aionios” is only a finite period, God cannot be “immortal” and only exist for a finite period at the same time. Thus “aionios” by definition means “eternal.”
[9]Galatians 6:8
(8) For he that soweth to his flesh shall of the flesh reap corruption; [φθορά/fthora] but he that soweth to the Spirit shall of the Spirit reap life everlasting. [αἰώνιος/aionios]
In this verse “aionios” is contrasted with “corruption.” “Fleshly” people reap “corruption” but spiritual people reap “life aionios,” i.e. “not corruption.” “Age(s), a finite period, is not opposite of “corruption.” Thus “aionios life” by definition here means “eternal/everlasting life.”
[10]John 6:58
(58) This is the bread that came down from heaven. Your ancestors ate manna and died, but whoever feeds on this bread will live forever.[αἰώνιος/aionios]
In this verse “aionios life” is contrasted with “death.” If “live aionios” is only a finite period, a finite period is not opposite “death.” Thus “aionios” by definition here means “eternal.”
[11]John 10:28
(28) I give them eternal [αἰώνιος/aionios] life, and they shall never [αἰών/aion] perish; no one will snatch them out of my hand.
Here “aionios” and “aion” are paired with “[not] snatch them out of my hand.” If “aion/aionios” means “age(s), a finite period,” that is not the opposite of “[not] snatch them out of my hand’” “Aionios life” by definition here means “eternal life.”
[12]1 John 2:17
(17) The world and its desires pass away, but whoever does the will of God lives forever. [αἰών/aion]
In this verse “aionios” is contrasted with “pass away,” “lives aionios” cannot mean a finite period, A “finite period” is not opposite of “pass away.” Thus “lives aionios” by definition here means “lives eternally.”
[13]1 Peter 5:10
(10) And the God of all grace, who called you to his eternal [αιωνιον/aionion] glory in Christ, after you have suffered a little while, [ολιγον/oligon] will himself restore you and make you strong, firm and steadfast.
In this verse “aionios” is contrasted with “little while” Does Jesus give His followers a finite period of glory then they eventually die? Thus “aionios” here means “eternal.”
[14]Romans 2:7
(7) To those who by persistence in doing good seek glory, honor and immortality, [ἀφθαρσία/apftharsia] he will give eternal [αἰώνιος/aionios] life.
In this verse “aionios” is paired with “immortality.” If “aionios” is only a finite period, believers cannot seek for “a finite period,” and “immortality” at the same time. But they can seek for “eternal life” and “immortality” at the same time. Thus by definition “aionios life” here means “eternal life.”
[15]1 Timothy 1:17.
(17) Now unto the King eternal, [αἰών/aion] immortal, [ ̓́αφθαρτος/aphthartos] invisible, the only wise God, be honour and glory for ever [αἰών/aion] and ever [αἰώνιος/aionios]. Amen.
In this verse “aion” is paired with “immortal.” “Aion” cannot mean “age(s),” a finite period and be immortal at the same time. Thus “aion” by definition here means “eternal.”
[16]Revelation 14:11
(11) And the smoke of their torment ascendeth up for ever and ever:[ εις αιωνας αιωνων/eis aionas aionon] and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name.
In this verse “aionas aionon torment” is paired with “no rest day or night.” If “aionas, aionon” means “a finite period” at some time they would rest, “Aionas, aionon” by definition here means “forever and forever.”
[17]John 10:28
(28) And I give unto them eternal [αιωνιον] life; and they shall never [εις τον αιωνα] perish, neither shall any man pluck them out of my hand.
In this verse “aionion” and “aiona” are paired with “[no man can] “pluck them out of my hand” If “aionion” and “aiona” are only a finite period then at some time they could be plucked out. “Aionion” and “aiona” by definition here mean eternal.
[18]John 3:15
(15) That whosoever believeth in him should not perish, but have eternal [αιωνιον] life.
In this verse “aionion” is paired with “shall not perish.” Believers could perish in a finite period, “aionion life” by definition here means eternal life.
[19]John 3:16
(16) For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting [αιωνιον] life.
In this verse “aionion” is paired with “should not perish.” Believers could eventually perish in a finite period, “aionion life” by definition here means eternal or everlasting life.
[20]John 5:24
(24) Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting [αἰώνιος] life, and shall not come into condemnation; but is passed from death unto life.
In this verse “aionios” is paired with “shall not come into condemnation” and “passed from life unto death.” “Aionios” does not mean “a finite period,” by definition here it means “eternal,” unless Jesus lets His followers come into condemnation and pass into death.
[21]Romans 5:21
(21) That as sin hath reigned unto death, even so might grace reign through righteousness unto eternal [αἰώνιος] life by Jesus Christ our Lord.
In this verse “aionios life” is contrasted with death. “A finite period life” is not opposite death, “eternal life” is. “Aionios life” by definition here means ‘eternal life.”
[22]Ephesians 3:21
(21) to him be glory in the church and in Christ Jesus throughout all generations, for ever [του αιωνος/tou aionios] and ever! [των αιωνων/ton aionion] Amen.
In this verse “tou aionios ton aionion” is paired with “throughout all generations.” "Age(s)" a finite period cannot refer to "all generations." By definition “tou aionios ton aionion” means forever and ever.
[23]John 8:51
(51) Very truly [αμην αμην/amen amen] I tell you, whoever obeys my word will never [ου μη εις τον αιωνα/ou mé eis ton aiona] see death."
According to noted Greek scholar Marvin Vincent "The double negative “ou mé” signifies in nowise, by no means." Unless Jesus is saying they will die, i.e. see death, unto the age. By definition aion means eternity.