Origen never used the English word "everlasting" & was a universalist, so to assume that he would have understood aionios in Mt 25:41,46 to mean "everlasting" is a big assumption and frankly, misleading....
How did Origen understand the word translated everlasting in 1 Corinthians 4:17-18, 1 Corinthians 5:1 ?
• Origen De Principiis. Book II. Chap. I.
6. Certainly, what some say of this world, that it is corruptible because it was made, and yet is not corrupted, because the will of God, who made it and holds it together lest corruption should rule over it, is stronger and more powerful than corruption, may more correctly be supposed of that world which we have called above a “non-wandering” sphere, since by the will of God it is not at all subject to corruption, for the reason that it has not admired any causes of corruption, seeing it is the world of the saints and of the thoroughly purified, and not of the wicked, like that world of ours. We must see, moreover, lest perhaps it is with reference to this that the apostle says, “While we look not at the things which are seen, but at the things which are not seen; for the things which are seen are temporal, but the things which are unseen are eternal. For we know that if our earthly house of this tabernacle were dissolved, we have a building of God, an house not made with hands, eternal in the heavens.” (2 Corinthians 4:18-5:1)
• Origen De Principiis. Book III.Chap. V
4. It seems worth while, then, to inquire what is meant by this new term; and I am, indeed, of opinion250 that, as the end and consummation of the saints will be in those (ages) which are not seen, and are eternal, we must conclude (as frequently pointed out in the preceding pages), from a contemplation of that very end, that rational creatures had also a similar beginning. And if they had a beginning such as the end for which they hope, they existed undoubtedly from the very beginning in those (ages) which are not seen, and are eternal.
• Origen De Principiis. Book III. Chap. VI
4. Respecting the body also, the apostle has said, “ We have a house not made with hands, eternal in the heavens,” (2Co_5:1) i.e., in the mansions of the blessed. And from this statement we may form a conjecture, how pure, how refined, and how glorious are the qualities of that body, if we compare it with those which, although they are celestial bodies, and of most brilliant splendour, were nevertheless made with hands, and are visible to our sight. But of that body it is said, that it is a house not made with hands, but eternal in the heavens. Since, then, those things “which are seen are temporal, but those things which are not seen are eternal,” (2Co_4:18) all those bodies which we see either on earth or in heaven, and which are capable of being seen, and have been made with hands, but are not eternal, are far excelled in glory by that which is not visible, nor made with hands, but is eternal.
6. And in this condition, also, we are to believe, that by the will of the Creator, it will abide for ever without any change, as is confirmed by the declaration of the apostle, when he says, “ We have a house, not made with hands, eternal in the heavens.”
• Origen De Principiis. Book I Chap VI
4. But since Paul says that certain things are visible and temporal, and others besides these invisible and eternal, we proceed to inquire how those things which are seen are temporal - whether because there will be nothing at all after them in all those periods of the coming world, in which that dispersion and separation from the one beginning is undergoing a process of restoration to one and the same end and likeness; or because, while the form of those things which are seen passes away, their essential nature is subject to no corruption.
• Origen De Principiis. Book II.Chap III
6. We must see, moreover, lest perhaps it is with reference to this that the apostle says, “While we look not at the things which are seen, but at the things which are not seen; for the things which are seen are temporal, but the things which are unseen are eternal. For we know that if our earthly house of this tabernacle were dissolved, we have a building of God, an house not made with hands, eternal in the heavens.” (2 Corinthians 4:18-5:1) And when he says elsewhere, “Because I shall see the heavens, the works of Thy fingers,” (Psa_8:3) and when God said, regarding all things visible, by the mouth of His prophet, “My hand has formed all these things,” (Isa_66:2) He declares that that eternal house in the heavens which He promises to His saints was not made with hands, pointing out, doubtless, the difference of creation in things which are seen and in those which are not seen.
• Origen Against Celsus. Book III. Chap. XLVII.
But it is probable that what is written by Paul in the first Epistle to the Corinthians, (cf. 1Co_1:18, etc.) as being addressed to Greeks who prided themselves greatly on their Grecian wisdom, has moved some to believe that it was not the object of the Gospel to win wise men. Now, let him who is of this opinion understand that the Gospel, as censuring wicked men, says of them that they are wise not in things which relate to the understanding, and which are unseen and eternal; but that in busying themselves about things of sense alone, and regarding these as all-important, they are wise men of the world: for as there are in existence a multitude of opinions, some of them espousing the cause of matter and bodies, and asserting that everything is corporeal which has a substantial existence, and that besides these nothing else exists, whether it be called invisible or incorporeal, it says also that these constitute the wisdom of the world, which perishes and fades away, and belongs only to this age, while those opinions which raise the soul from things here to the blessedness which is with God, and to His kingdom, and which teach men to despise all sensible and visible things as existing only for a season, and to hasten on to things invisible, and to have regard to those things which are not seen, - these, it says, constitute the wisdom of God.
• Origen Against Celsus. Book VI Chap. XIX
Our Paul, moreover, educated by these words, and longing after things “supra-mundane” and “super-celestial,” and doing his utmost for their sake to attain them, says in the second Epistle to the Corinthians: “ For our light affliction, which is but for a moment, worketh for us a far more exceeding and eternal weight of glory; while we look not at the things which are seen, but at the things which are not seen: for the things which are seen are temporal; but the things which are unseen are eternal.” (cf. 2Co_4:17, 2Co_4:18)
Chap. XX.
Now, to those who are capable of understanding him, the apostle manifestly presents to view “things which are the objects of perception,” calling them “things seen;” while he terms “unseen,” things which are the object of the understanding, and cognisable by it alone. He knows, also, that things “seen” and visible are “temporal,” but that things cognisable by the mind, and “not seen,” are “eternal;” and desiring to remain in the contemplation of these, and being assisted by his earnest longing for them, he deemed all affliction as “light” and as “nothing,” and during the season of afflictions and troubles was not at all bowed down by them, but by his contemplation of (divine) things deemed every calamity a light thing, seeing we also have “a great High Priest,” who by the greatness of His power and understanding “has passed through the heavens, even Jesus the Son of God,” who has promised to all that have truly learned divine things, and have lived lives in harmony with them, to go before them to the things that are supra-mundane; for His words are: “That where I go, ye may be also.”
• Origen Against Celsus. Book VII Chap. XXXII.
Then, again, as there is “a tabernacle” and “an earthly house” which is in some sort necessary for this tabernacle, Scripture teaches us that “the earthly house of this tabernacle shall be dissolved,” but that the tabernacle shall “be clothed upon with a house not made with hands, eternal in the heavens.” (2Co_5:1)
De Principiis. Book IV. Chap. I
36. And not only so, but because the nature of Father, and Son, and Holy Spirit, whose intellectual light alone all created things have a share, is incorruptible and eternal, it is altogether consistent and necessary that every substance which partakes of that eternal nature should last for ever, and be incorruptible and eternal, so that the eternity of divine goodness may be understood also in this respect, that they who obtain its benefits are also eternal.