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.
Source: St. Basil the Great, Commentary on the Prophet Isaiah, translated by Nikolai A. Lipatov, p. 275-276
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; which eats up, as if it were hay, all defiled matter, and consumes all vanity and vice."
Source: Oracles 39:19
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)
"Our Lord is the One who delivers man, and who heals the inventor of evil himself."
Source: The Great Catechism (Oratio Catechetica.)
St. Ambrose (Doctor of The Church. Bishop of Milan from 374 A.D. to 397 A.D. Venerated as Saint by Catholics and Orthodox)
Our Savior has appointed two kinds of resurrection in the Apocalypse. 'Blessed is he that hath part in the first resurrection,' for such come to grace without judgment. As for those who do not come to the first, but are reserved unto the second resurrection, these shall be disciplined until their appointed times, between the first and the second resurrection; or, if they should not have fulfilled them then, they shall remain still longer in punishment until they have paid the very last farthing.
Source: Psalmum I Enarratio (Exposition on Psalm 1), section 36.
And
"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."
Source: Exposition of the Christian Faith (also known as De Fide ad Gratianum), Book V, Chapter 14, Section 181
Also
"The mystery of the cross of the Lord is a heavenly thing; and it was wrought not only for men, but also for the angels. For those who are in the heavens may be confirmed, and those who are in the lower parts may be restored."
Source: De fide ad Gratianum (on the Christian Faith), Book I, Chapter 5 section 43.