The Greek word
aiónios is mistranslated in some instances into "forever" or "everlasting" or into "eternity". My understanding is that it
can mean forever but oftentimes means for an age or for a time.
I like the English Standard Version (esv) Bible for its ease of reading but I have learned to double-check some verses with Young's Literal Translation (ylt) Bible (created in 1898) as it more accurately translates that word.
Here are some examples of verses translated by the esv vs. te ylt editions.
Mathew 25:46 ESV
And these will go away into eternal punishment, but the righteous into eternal life.
Mathew 25:46 YLT
And these shall go away to punishment age-during, but the righteous to life age-during
Truly, truly, I say to you, whoever hears my word and believes him who sent me has eternal life. He does not come into judgment, but has passed from death to life.
John 5:24
Young's Literal Translation
24 `Verily, verily, I say to you -- He who is hearing my word, and is believing Him who sent me, hath life age-during, and to judgment he doth not come, but hath passed out of the death to the life.
2 Thessalonians 1:9
English Standard Version
9 They will suffer the punishment of eternal destruction, away from[
a] the presence of the Lord and from the glory of his might,
2 Thessalonians 1:9
Young's Literal Translation
9 who shall suffer justice -- destruction age-during -- from the face of the Lord, and from the glory of his strength,