Well I guess Jesus was lying.
John 3:15
(15) That whosoever believeth in him should not perish, but have eternal [aionion] life.
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,” twice! Believers could eventually perish in a finite period, thus by definition “aionion life” here means eternal or everlasting life.
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.
Mat 25:46 And these shall go away into everlasting [aionios] punishment:[kolasis] but the righteous into life eternal.
Some folk argue that "aionios" does not mean eternal but see John 3:15-16 and John 3:36, above. And that "kolasis" translated "punishment" in Matt 25:46 "really means "pruning" or "correction."
"Kolasis" occurs in only one other verse in the N.T. 1 John 4:18
1 John 4:18
(18) There is no fear in love; but perfect love casteth out fear: because fear hath torment.[kolasis] He that feareth is not made perfect in love.
In this verse the one who has "kolasis" is not corrected i.e. "not made perfect."
If you understand scripture you can explain 1John 4:18 like this. There is no fear in love ( if you are in love you are in God and if you are in God you have no fear) if you are in fear you are under Gods kolasis punishment and those who are under Gods kolasis punishment are not yet in God so they stand in the punishment, but once they repent they are no longer in His punishment but are in love. And yes that can happen even after the mortal body dies.