[T]he Orthodox Church is far from the excessive optimism of those who maintain that at the end of time God’s mercy will extend to all of unrighteous humanity and all people, including great sinners, and together with them the devil and his demons will be saved in a lofty form by will of the God Who is good. Origen expressed this idea in the third century, Origen whose teaching on apokatastasis (“universal restoration”) was condemned in its entirety by an Ecumenical Council as contrary to the teachings of the Fathers of the Church.
…However, such a theory, first of all, contradicts the Christian vision of the historical process as a path to the final transfiguration into a better state, and not at all as a return to the initial condition. Protopresbyter Georges Florovsky writes that “the whole pathos of Origen’s system is concluded in the cancellation, the abolition of the enigma of time and being. It is precisely in this intimate thought that his famous teaching of the ‘universal restoration (apokatastasis) lies… Apokatastasis is the rejection of history. The whole content of historical time is dispersed without memory or consequence. And ‘after’ history remains only that which was already ‘before’ history.” (Dogmat i istoriya, Moscow 1995, 294-295)
…Origenist apokatastasis radically contradicts the basic fundamentals of Christian morality. Indeed, what moral sense is there throughout the whole drama of human history if good and evil end up being equal in the eyes of divine mercy and just judgment? What meaning does the separation of the sheep and the goats at the Last Judgment have, if the good is not the only and absolute criterion by which this division occurs, or if this division bears a temporary character? What meaning is there in suffering, prayer, ascetical efforts, the fulfillment of the Gospel commandments, if the righteous will be sooner or later equal to sinners? As Emperor Justinian asked, is it fair that “those who led a life full of perfection to the end should be united with the lawless and pederasts, and to acknowledge that both the former and the latter should enjoy equal blessings?” (Letter to the Holy Council on Origen and His Accomplices) The Origenist understanding of apokatastasis does not give an answer even to one of these questions.
Origen’s supposition on the potential salvation of the devil and his demons is in radical opposition to Church Tradition… the devil and demons’ falling away from God is perceived in Christian Tradition as final and irrevocable. In the words of John of Damascus, repentance is impossible both for angels and for the devil and his demons. It is impossible for the former because they are incorporeal and do not sin, and for the latter because they cannot change and be saved, but the unquenchable fire and eternal torment await them.
Origen’s view on the non-eternal nature of the torment… directly contradicts the Gospel, where this torture and perdition of sinners is repeatedly called eternal… It is true that Origen placed much attention on the fact that the adjective “eternal” (aionios) comes from the word “age” (aion) and therefore can indicate a certain length, though not a never-ending stretch, of time: in Origen’s opinion, hellfire is exactly like this — eternal, but not never-ending. The argument is on the two notions of the word “eternity” — on the eternity of God in comparison to which nothing created is eternal, and on eternity as an endless length of time. However, such a distinction is absent in the very texts of Holy Scripture that speak of eternal torment and eternal perdition, as well as any kind of allusions to the possibility of a spiritual progression and subsequent salvation of the devil and his demons.
…The teaching on apokatastasis and universal salvation gained a whole group of supporters in the form of theologians and philosophers of the Russian diaspora in the twentieth century. The consistent and decisive proponents of this teaching were Archpriest Sergius Bulgakov and N.A. Berdiaev. V.N. Lossky was more cautious, yet still spoke out in favor of this teaching. Metropolitan Anthony of Sourozh in particular also repeatedly defended it in his compositions… However, the opinions of individual theologians and philosophers defending the teaching of universal salvation do not grant it legitimacy. The Church condemned the concept of apokatastasis. (Orthodox Christianity Vol. II: Doctrine and Teaching of the Orthodox Church, pp. 557-570)