As the Greek word aionios is derived from aion (age), why cannot aionios be translated as age–lasting in Matt. 25: 41 (“Go from me, cursed, into eternal fire”)?
The background to this question is the widespread denial of eternal punishment in the professing Church. The adjective aionios is indeed derived from the noun aion and hence the noun does determine its meaning. However, the meaning of aion is not restricted to time. While Scripture must ever be used to interpret Scripture, the meaning of words employed by the Spirit of God in NT Greek can often be understood by reference to those who wrote at that time outside of the Scriptures. One such writer was Philo, a Hellenistic Jew. He wrote these words: en aioni de oute pareleluthen ouden, oute mellei, alla monon iphesteken (in eternity nothing is passed, nothing is about to be, but only subsists). The word he uses for eternity is aioni, the dative of the word aion. One can hardly argue that Philo was ignorant of his native tongue! If aion can mean eternity, then aionios can mean eternal and not just age–lasting.
In the Scriptures we find that there are many passages in which eternal is the only sensible translation of aionios. Thus we read of “the eternal God” (Rom. 16: 26), whose glory is “eternal” (1 Pet. 5: 10). Would any argue that God is just age–lasting or that His glory is limited to time? We are told that “the things that are seen [are] for a time, but those that are not seen eternal” and that our present “momentary [and] light affliction works for us in surpassing measure an eternal weight of glory” (2 Cor. 4: 17, 18—my emphasis). The Apostle is clearly making contrasts in the passage. What contrast is there between things that are temporal and those that are age–lasting? None whatsoever! The only translation that makes sense requires the word eternal for aionios. In Hebrews we have a whole series of things that are said to be aionios: “eternal salvation”, “eternal redemption”, “eternal Spirit”, “eternal inheritance” and “eternal covenant” (Heb. 5: 9; 9: 12, 14, 15; 13: 20). All these must be eternal, and most are contrasted with what is temporal. Significantly, the series also includes “eternal judgment” (Heb. 6: 2). Apart from prejudice, there are no grounds for saying that aionios should be translated eternal elsewhere in Hebrews but not in chapter six.
The Lord Himself provides compelling evidence of the unending nature of the judgment to come. In Matt. 18: 8 He says “into eternal fire”. In the parallel passage in Mark 9, He is recorded as using a different phrase, namely “fire unquenchable” and defines this further with the words “where their worm dies not, and the fire is not quenched” (vs 43, 48—my emphasis). To argue that the fire of Matt. 18: 8 is just age–lasting would mean that in Mark 9 there must come a time where their worm does die and the fire is quenched! Hence the only admissible meaning is that of eternal fire.
The verse quoted in the question before us speaks of the Lord telling certain persons to “Go from me, cursed, into eternal fire” (Matt. 25: 41). The phrase here in Greek for “into eternal fire” is exactly identical to that in Matt. 18: 8 and hence the meaning is identical and the fire is eternal, not age–lasting. Travel down only five verses in Matt. 25 and you read: “And these shall go away into eternal punishment, and the righteous into life eternal” (v46). Here we have two classes spoken of in the same verse, and if the condition of the one is unending, then so is that of the other. If we deny that the punishment is unending in its duration then we cannot justly call the life eternal either.
Finally, it might be as well to show that the noun aion from which aionios is derived can mean eternity in the Scriptures. When the Lord spoke about the sin against the Holy Spirit He said “to eternity (aion) has no forgiveness; but lies under the guilt of an everlasting (aionios) sin” (Mark 3: 29). If this were to read ‘For an age has no forgiveness; but lies under the guilt of an age–lasting sin’, it would contradict the parallel passage in Matt. 12: 32: “it shall not be forgiven them, neither in this age (aion) nor in the coming [one]”. Two ages only are recognised and forgiveness for this sin is found in neither. One might also ask why the sin against the Holy Spirit can be forgiven at some future date (for that is the logical conclusion of the argument for age–lasting) but not at the time when the Lord was speaking.
Does any of this matter? Indeed it does! The writer of Hebrews speaks of “eternal judgment” as foundational (see Heb. 6: 1, 2). The unwarranted tampering with the plain meaning of aionios in its connection with fire and punishment leads, inevitably, to a diminished view of the salvation of God and a weakening of the believer’s eternal security. “Eternal fire” (Matt. 25: 41) means what it says!