When Jesus says never does He mean "never" or sometime? See Matt 7:23, below.
Jesus taught,
• “Depart from me, ye cursed, into everlasting [aionios] fire, prepared for the devil and his angels:” Matthew 25:41
• "these shall go away into eternal [ainios] punishment, Matthew 25:46"
• "the fire of hell [Γέεννα/gehenna] where the fire is not quenched and the worm does not die, 3 times Mark 9:43-48"
• "cast into a fiery furnace where there will be wailing and gnashing of teeth,” Matthew 13:42, Matthew 13:50
• “But whoso shall offend one of these little ones which believe in me, it were better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea.” Matthew 18:6 [a fate worse than death]
• “And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.” Matthew 7:23
• “woe unto that man by whom the Son of man is betrayed! it had been good for that man if he had not been born. ” Matthew 26:24 [fate worse than death]
• “But I say unto you, that it shall be more tolerable in that day for Sodom, than for that city.” Luke 10:12
…..These teachings tacitly reaffirmed and sanctioned a then existing significant Jewish view of eternal hell, outlined above.
In Matt. 18:6, 26:24 and Luk 10:12, see above, Jesus teaches that there is a punishment worse than death or nonexistence.
…..Some people claim that “aion/aionios” never means eternity/eternal because they sometimes refer to things which are not eternal.
However, neither word is ever defined/described, by other adjectives or adjectival phrases, as meaning a period of time less than eternal, in the New Testament, as in the following verses.
…..Jesus used “aionios” twenty eight [28] times. He never used “aionios” to refer to anything ordinary or mundane that was not or could not be eternal.
…..In the following ten verses Jesus defines “aionios” as “eternal.”
[1] Luke 1:33
(33) And he shall reign [basileusei][Vb] over the house of Jacob for ever; [aionas] and of his kingdom [basileias][Nn] there shall be no end.[telos]
In this verse the reign/basileusei, which is the verb form of the word, is "aionas" and of the kingdom/basileias, the noun form of the same word, "there shall be no end.” “Aionas” by definition here means eternal.
[2] 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.[aionios]
In this verse Jesus juxtaposes “aionios life” with “death.” If “live aionios” is only a finite period, a finite period is not opposite “death.” Thus “aionios” by definition here means “eternal.”
[3] John 10:28
(28) I give them eternal [aionios] life, and they shall never [aion] perish; no one will snatch them out of my hand.
In this verse Jesus parallels “aionios” and “aion” 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.”
[4]John 3:15
(15) That whosoever believeth in him should not perish, but have eternal [aionion] life.
[5] 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 [aionion] life.
In these two verses Jesus parallels “aionion” with “should not perish.” Believers could eventually perish in a finite period, thus by definition “aionion life” here means eternal or everlasting life.
[6]John 5:24
(24) Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting [aionios] life, and shall not come into condemnation; but is passed from death unto life.
In this verse Jesus parallels “aionios” with “shall not come into condemnation” and “passed from death unto life.” “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.
[7]John 3:36 He that believeth on the Son hath everlasting [aionios] life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.
In this verse Jesus juxtaposed aionios life with “shall not see life.” If aionios means an indefinite age that is not opposite “shall not see life” By definition aionios means eternal.
[8]John 4:14 But whosoever drinketh of the water that I shall give him shall never [ου μη/ou mé] thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting [aionios] life.
In this verse Jesus paralleled aionios with “shall [ου μη/ou mé][fn] never thirst.” If aionios means an indefinite age that is not opposite “shall never thirst.” By definition aionios means eternal. See note [fn] on “ou mé” below.
[9]John 6:27
(27) Labour not for the meat which perisheth, but for that meat which endureth unto everlasting [aionios] life, which the Son of man shall give unto you: for him hath God the Father sealed.
In this verse Jesus contrasted “aionios meat” with “meat that perishes” If aionios means an indefinite age that is not opposite “meat that perishes.” By definition aionios means eternal.
[10]John 8:51
(51) Very truly [amen amen] I tell you, whoever obeys my word will never [ou mé eis ton aiona][fn] see death."
[fn]●The double negative [ου μη] signifies in nowise, by no means. Θεωρήσῃ[theōrésé], denoting steady, protracted vision, is purposely used, because the promise contemplates the entire course of the believer's life in Christ. It is not, shall not die forever, but shall live eternally.[Vincent word studies]
● ④οὐ marker of reinforced negation, in combination w. μή, οὐ μή has the effect of strengthening the negation (Kühner-G. II 221–23; Schwyzer II 317; Mlt. 187–92 [a thorough treatment of NT usage]; B-D-F §365; RLudwig: D. prophet. Wort 31 ’37, 272–79; JLee, NovT 27, ’85, 18–23; B-D-F §365.—Pla., Hdt. et al. [Kühner-G. loc. cit.]; SIG 1042, 16; POxy 119, 5, 14f; 903, 16; PGM 5, 279; 13, 321; LXX; TestAbr A 8 p. 85, 11 [Stone p. 46]; JosAs 20:3; GrBar 1:7; ApcEsdr 2:7; Just., D. 141, 2). οὐ μή is the most decisive way of negativing something in the future.
Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000)A Greek-English lexicon of the New Testament and other early Christian Literature.(3rd Ed). Chicago: University of Chicago Press.
● The combinations with οὐ μή also be noticed as, ουδεν οὐ μή (Lu. 10:19); οὐ μή se σε άνο ουδ ου σε εγκαταιπο (Heb. 13:5); ουκετι οὐ μή (Rev. 18:14). There is no denying the power of this accumulation of negatives. Cf. the English hymn "I'll never, no never, no never forsake."
Grammar Of The Greek New Testament In The Light Of Historical Research
By A. T. Robertson, M.A., D.D., Ll.D., Litt.D. p.1165.