Apocatastasis

definition:
Apocatastasis - final reconcilation; the universal redemption of all souls after passing through a purgatorial fire, or direct entry into paradise.

Apocatastasis
http://www.newadvent.org/cathen/01599a.htm
(Greek, apokatastasis; Latin, restitutio in pristinum statum, restoration to the original condition).

"A name given in the history of theology to the doctrine which teaches that a time will come when all free creatures will share in the grace of salvation; in a special way, the devils and lost souls.This doctrine was explicitly taught by St. Gregory of Nyssa, and in more than one passage. It first occurs in his "De animâ et resurrectione" (P.G., XLVI, cols. 100, 101) where, in speaking of the punishment by fire assigned to souls after death, he compares it to the process whereby gold is refined in a furnace, through being separated from the dross with which it is alloyed. The punishment by fire is not, therefore, an end in itself, but is ameliorative; the very reason of its infliction is to separate the good from the evil in the soul. The process, moreover, is a painful one; the sharpness and duration of the pain are in proportion to the evil of which each soul is guilty; the flame lasts so long as there is any evil left to destroy. A time, then, will come, when all evil shall cease to be since it has no existence of its own apart from the free will, in which it inheres; when every free will shall be turned to God, shall be in God, and evil shall have no more wherein to exist. Thus, St. Gregory of Nyssa continues, shall the word of St. Paul be fulfilled: Deus erit omnia in omnibus (1 Corinthians 15:28), which means that evil shall, ultimately, have an end, since, if God be all in all, there is no longer any place for evil (cols. 104, 105; cf. col. 152).
etc.

The dogmatic relation of the Orthodox Church to the doctrine of Apocatastasis
http://orthodoxwiki.org/Apocatastasis

"First, Origin's doctrine of apocatastasis has been condemned in three local councils in the fifth century: an Alexandrian council, under the presidency of Patriarch Pheofilos, a Cyprian council, under presidency of St. Epifanios of Cyprus, and a Roman council, under the presidency of Pope Anastasius I. The decision of the Council (also Synod) of Constantinople in 453, confirmed by the Fifth Ecumenical Council's anathemas in 553: "If anyone shall say that all reasonable beings will one day be united in one,...moreover, that in this pretended apocatastasis, spirits only will continue to exist, as it was in the reigned pre-existence: let him be anathema."

Greek, apokatastasis: the time for restoring everything to perfection,
states restored by benefactors to normal conditions and stability

see Peter's words in Acts 3:21:

NET Acts 3:21 This one heaven must receive until the time all things are restored, which God declared from times long ago through his holy prophets.

NIV Acts 3:21 He must remain in heaven until the time comes for God to restore everything, as he promised long ago through his holy prophets.

NKJV Acts 3:21 "whom heaven must receive until the times of restoration of all things, which God has spoken by the mouth of all His holy prophets since the world began.

NRSV Acts 3:19-26
19 Repent therefore, and turn to God so that your sins may be wiped out,
20 so that times of refreshing may come from the presence of the Lord, and that he may send the Messiah appointed for you, that is, Jesus,
21 who must remain in heaven until the time of universal restoration that God announced long ago through his holy prophets. ...
26 When God raised up his servant, he sent him first to you, to bless you by turning each of you from your wicked ways."

YLT Acts 3:21 whom it behoveth heaven, indeed, to receive till times of a restitution of all things, of which God spake through the mouth of all His holy prophets from the age.