St. Basil (Doctor of The Church. Bishop of Cappadocia from 370 A.D. until his death in 379 A.D.)
We have heard before how many names of the Lord we have already been taught by the prophet. ‘Behold, a virgin shall conceive in her womb and shall bear a Son, and they shall call his name Emmanuel.’ Here His name is called ‘Messenger of great counsel’. He is the one Who made known the great counsel kept secret for the ages (Col. 1:26) and not manifested to other generations (Eph. 3:5). He is the one Who announced and manifested among the Gentiles His inscrutable wealth (Eph. 5:8), in order that the Gentiles should be fellow-heirs and the same body (Eph. 3:6) of Him whose sovereignty is upon His shoulder, that is Whose kingdom and power are on the cross; as having been lifted up on the cross He drew all to Himself (John 12:32). […] There is no end of His peace, for the reason that it is a supramundane gift. For had it been from the world, it would have lasted only as long as the world exists. But now, he who has accepted His peace and preserved it shall live with the good things of His peace for ever. The peace of Solomon was limited to the recorded years, whereas the peace from the Lord is co-extensive with the whole of eternity, being unlimited and boundless. For all shall be subjected to Him and all shall recognise His mastery, and when God shall be all in all (1 Cor. 15:28), and those making an uproar by their apostasies are silenced, all in peaceful harmony shall praise God with hymns.
--St. Basil the Great, Commentary on the Prophet Isaiah, translated by Nikolai A. Lipatov, p. 275-276
St. Gregory Nazianzus (Doctor of The Church, Bishop of Constantinople from 379 to 390 A.D.)
These, if they will, may go Christ's way, but if not let them go their way. In another place perhaps they shall be baptized with fire, that last baptism, which is not only painful, but enduring also in it’s effects; which eats up, as if it were hay, all defiled matter, and consumes all vanity and vice.
--Oracles 39:19
And
...that as for my sake He was called a curse, Who destroyed my curse; and sin, who taketh away the sin of the world; and became a new Adam to take the place of the old, just so He makes my disobedience His own as Head of the whole body. As long then as I am disobedient and rebellious, both by denial of God and by my passions, so long Christ also is called disobedient on my account. But when all things shall be subdued unto Him on the one hand by acknowledgment of Him, and on the other by a reformation, then He Himself also will have fulfilled His submission, bringing me whom He has saved to God. For this, according to my view, is the subjection of Christ; namely, the fulfilling of the Father's Will."
--Gregory of Nazianzus, Oration 30.5-6, PG 36:110B-C
Gregory of Nyssa (Bishop of Nyssa from 372 to 376 and from 378 until his death in 394. Venerated as a Saint by Orthodox, Catholics, and Anglicans. Declared the Father of Fathers by the Seventh Ecumenical Council)
For it is as when some worthless material has been mixed with gold, and the gold-refiners burn up the foreign and refuse part in the consuming fire, ad so restore the more precious substance to its natural lustre: not that the separation is effected without difficulty, for it takes time for the fire by its melting force to cause the baser matter to disappear; but for all that, this melting away of the actual thing that was embedded in it to the injury of its beauty is a kind of healing of the gold. In the same way when death, and corruption, and darkness, and every other offshoot of evil had grown into the nature of the author of evil, the approach of the Divine power, acting like fire, and making that unnatural accretion to disappear, thus by purgation of the evil becomes a blessing to that nature, though the separation is agonizing. Therefore even the adversary himself will not be likely to dispute that what took place was both just and salutary, that is, if he shall have attained to a perception of the boon. For it is now as with those who for their cure are subjected to the knife and the cautery; they are angry with the doctors, and wince with the pain of the incision; but if recovery of health be the result of this treatment, and the pain of the cautery passes away, they will feel grateful to those who have wrought this cure upon them.
St. Gregory of Nyssa, The Catechetical Oration, Chapter 38. Translated by William Moore and Henry Austin Wilson. In Nicene and Post-Nicene Fathers, Second Series, Volume 5. Edited by Philip Schaff and Henry Wace. Buffalo: Christian Literature Publishing Co., 1893.
And
"For it is clear that God will be 'all in all' when there is no evil remaining in existence.
--Gregory of Nyssa, On The Soul and the Resurrection.
St. Ambrose (Doctor of The Church. Bishop of Milan from 374 A.D. to 397 A.D. Venerated as Saint by Catholics and Orthodox)
When therefore, all things have become subject to Christ, through Christ's obedience, so that all bend their knees in His name, then He Himself will be all in all. For now, since all do not believe, all do not seem to be in subjection. But when all have believed and done the will of God, then Christ will be all and in all.
--St. Ambrose, Exposition of the Christian Faith (also known as De Fide ad Gratianum), Book V, Chapter 14, Section 181
Theodore of Mopsuestia (Bishop of Mopsuestia from 392 A.D until his death in 428 A.D.)
The wicked who have committed evil the whole period of their lives shall be punished till they learn that, by continuing in sin, they only continue in misery. And when, by this means, they shall been brought to fear God, and to regard Him with good will, they shall obtain the enjoyment of His grace.
--Bibliotheca Orientalis
Diodore of Tarsus (Bishop of Tarsus from 378 until his death in 393 A.D.)
For the wicked there are punishments, not perpetural, however, lest the immortality prepared for them should be a disadvantage, but they are to be purified for a brief period according to the amount of malice in their works. They shall therefore suffer punishment for a short space, but immortal blessedness having no end awaits them. For the penalties to be inflicted for their many and grave sins are very far surpassed by the magnitude of the mercy to be showed to them."
--Bibliotheca Orientalis.
Theodoret the Blessed (Bishop of Cyrrhus in Syria from 423 to 457 A.D.)
But in the future life corruption ceasing and immortality being conferred, the passions have no place, and these being removed, no kind of sin is committed. So from that time God is all in all, when all, freed from sin, and turned to him, shall have no inclination to evil.
--Theodoret of Cyrus, Commentary on 1 Corinthians 15:28_, PG 82:360A; trans. Robert Charles Hill, _Commentary on the Letters of St. Paul_ vol. 1 [Holy Cross Orthodox Press, 2001]
And
In the present life God is in all, for his nature is without limits, but is not all in all. But in the coming life, when mortality is at an end and immortality granted, and sin has no longer any place, God will be all in all.
--Theodoret of Cyrus, Commentary on Ephesians 1:23, PG 82:513B; trans. Hill vol. 1
And
"For the Lord, who loves man, punishes medicinally, that he may check the course of impiety."
--Theodoret of Cyrus, Commentary on Ephesians 1:23, PG 82:513B-C