“Lasting” is not an interpretation of “aiōnios.” It is its meaning. Even “long lasting” is going too far.
The Greek noun “kolasis” (found in Matthew 25:46) is derived from the verb “kolazō” which originally meant “to prune” as in pruning trees. Trees are often pruned in order to correct their growth, and so the verb as well as the noun began to be applied to any kind of correction.
Let’s look at how Matthew 25:46 reads when we translate “aiōnios” at “eternal”:
And these (the goats) will go away into eternal correction, but the righteous into eternal life."
How can correction be eternal? Would the correction ever be accomplished? If not, it would not be correction. If it were accomplished, it would not be eternal.
Mark 3:29 but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin"—
How can a sin be eternal?
Luke 16:9 "And I say to you, make friends for yourselves by means of the wealth of unrighteousness, so that when it fails, they will receive you into the eternal dwellings.
If this means eternal dwellings in heaven, then this verse implies that you can buy your way there.
Titus 1:2 in hope of eternal life which God, who never lies, promised before eternal times.
How can there be a period of time before eternal times? “Before eternal times” is the literal translation if the Greek word “aiōnios” means “eternal”.
Philemon 1:15 Perhaps this is why he was parted from you for a while, that you might have him back for eternally.
How could Philemon have his slave back eternally? Would the slave continue to serve him forever in the next life?
Jude 1:7 just as Sodom and Gomorrah and the surrounding cities, which likewise acted immorally and indulged in unnatural lust, serve as an example by undergoing a punishment of eternal fire.
Did Sodom and Gomorrah undergo punishment in eternal fire? Didn’t that fire go out ages ago?
In secular Greek literature, the word “aiōnios” meant “lasting” or “enduring”. In the first century before Christ, Diodorus Siculus, a Greek historian, wrote:
“The second wall is in all other respects like the first, but of twice the height. The third circuit is rectangular in plan, and is sixty cubits in height, build of a stone hard and naturally “aiōnios”.
Was the stone naturally eternal?
Flavius Josephus in Wars of the Jews, wrote:
“…Jonathan condemned to “aiōnios” imprisonment.” Was Jonathan condemned to eternal imprisonment? It is said that his imprisonment was for a period of three years.
The Greek adjective “aiōnios” is derived from the Greek noun “aiōn”, which means “age”.
Chystostum (A.D. 347-407) understood “aiōnios” as meaning lasting for an age. Here is what he wrote:
“Here again [Paul] means that Satan occupies the space under Heaven, and that the incorporeal powers are spirits of the air, under his operation. For that his kingdom is “aiōnios”. In other words, it will cease with the present “aiōn” (age), hear what he says at the end of the epistle;”
Homily of the Epistle of Saint Paul to the Ephesians, Homly IV)