It is sometimes argued that Gregor of Nyssa did not clearly teach universal restitution, as some of his remarks on salvation and eschatology in his Great Catechism seems to only ambivalently assert this issue. But more clear are Gregory’s statements in the short treatise on Paul’s First Epistle to the Corinthians 15:28, where Paul says that “the Son will be subjected to him who has subjected all things to himself”. Gregory argues that the subjection spoken of by Paul is in both instances not a forced, but a free and joyful subjection, that leads to salvation of all who are subjected to God through Christ.
The only available English translation of the treatise – often referred to by its Latin title “In Illud, Tunc et ipse filius” – was made by Casimir McCambley and published under the title “When (the Father) Will Subject All Things to (the Son), Then (the Son) Himself Will Be Subjected to Him (the Father) Who Subjects All Things to Him (the Son). A treatise on First Corinthians 15.28.” in Greek Orthodox Theological Review 28 (1983), p. 1-25.
As I do not own the rights for the translation I will only quote a few passages. The full text is still available here.
It is time now to quote the apostle himself on these matters. “For as in Adam all die, so also in Christ shall all be made alive. But each in his own order: Christ the first fruits, then at his coming those who belong to Christ. Then comes the end when he delivers the kingdom to God the Father after destroying every rule and every authority and power. For he must reign until he has put all his enemies under his feet. The last enemy to be destroyed is death. ‘For God has put all things in subjection under his feet’ [a reference to Ps 8.6]. But when it says, ‘All things are put in subjection under him,’ it is plain that he is accepted who put all things under him. When all things are subjected to him, then the Son himself will also be subjected to him who puts all things under him, that God may be everything to everyone” [1 Cor 15.22-28].
Paul signifies, by the Son’s subjection, the destruction of death. Therefore, these two elements concur, that is, when death will be no more, and everything will be completely changed into life. The Lord is life. According to the apostle, Christ will have access to the Father with his entire body when he will hand over the kingdom to our God and Father. Christ’s body, as it is often said, consists of human nature in its entirety to which he has been united. Because of this, Christ is named Lord by Paul, as mediator between God and man [1 Tim 2.5]. He who is in the Father and has lived with men accomplishes intercession. Christ unites all mankind to himself, and to the Father through himself, as the Lord says in the Gospel, “As you, Father, are in me, and I am in you, that they may be one in us” [Jn 17.21]. This clearly shows that having united himself to us, he who is in the Father effects our union (sunapheia) with this very same Father .
The exposition of the term ‘subjection’ as used here does not mean the forceful, necessary subjection of enemies as is commonly meant; while on the other hand, salvation is clearly interpreted by subjection. However, clear proof of the former meaning is definitely made when Paul makes a twofold distinction of the term ‘enemy.’ He says that enemies are to be subjected; indeed, they are to be destroyed. Therefore, the enemy to be blotted out from human nature is death, whose principle is sin along with its [M.1325] domination and power. In another sense, the enemies of God which are to be subjected to him attach themselves to sin after deserting God’s kingdom. Paul mentions this in his Epistle to the Romans: “For if we have been enemies, we have been reconciled to God” [Rom. 5:10]. Here Paul calls subjection reconciliation, one term indicating salvation by another word. For as salvation is brought near to us by subjection, Paul says in another place, “Being reconciled, we shall be saved in this life” [Rom 5.10]. Therefore, Paul says that such enemies are to be subjected to God and the Father; death no longer is to have authority. This is shown by Paul saying, “Death will be destroyed,” a clear statement that the power of evil will be utterly removed: persons are called enemies of God by disobedience, while they who have become the Lord’s friends are persuaded by Paul saying, “We are ambassadors for Christ, as though God did beseech you by us: ‘Be reconciled to God [2 Cor 6:20] .
According to the promise made in the Gospel, we are no longer slaves of the Lord; but once reconciled, we are numbered among his friends. However, “it is necessary for him to reign, until he places his enemies under his feet.” We reverently take this, I believe, as Christ valiantly holding sway in his power. Then the strong man’s ability in battle will cease when all opposition to the good will be destroyed. Once the entire kingdom is gathered to himself, Christ hands it over to God and the Father who unites everything to himself. For the kingdom will be handed over to the Father, that is, all persons will yield to God [Christ], through whom we have access to the Father.
When all enemies have become God’s footstool, they will receive a trace of divinity in themselves. Once death has been destroyed – for if there are no persons who will die, not even death would exist – then we will be subjected to him; but this is not understood by some sort of servile humility. Our subjection, however, consists of a kingdom, incorruptibility and blessedness living in us; this is Paul’s meaning of being subjected to God. Christ perfects his good in us by himself, and effects in us what is pleasing to him.