Here is a piece from the New Advent site that Strider shared with me:
The doctrine of the
apokatastasis is not, indeed, peculiar to
St. Gregory of Nyssa, but is taken from Origen, who seems at times reluctant to decide concerning the question of the eternity of punishment. Tixeront has well said that in his “De principiis” (I, vi, 3) Origen does not venture to assert that all the
evil angels shall sooner or later return to
God (P.G., XI, col. 168, 169); while in his “Comment. in Rom.”, VIII, 9 (P.G., XIV, col. 1185), he states that Lucifer, unlike the Jews, will not be converted, even at the end of time. Elsewhere, on the other hand, and as a rule, Origen teaches the
apokatastasis, the final restoration of all intelligent creatures to friendship with
God. Tixeront writes thus concerning the matter: "Not all shall enjoy the same happiness, for in the Father’s house there are many mansions, but all shall attain to it. If Scripture sometimes seems to speak of the punishment of the wicked as eternal, this is in order to terrify sinners, to lead them back into the right way, and it is always possible, with attention, to discover the true meaning of these texts. It must, however, always be accepted as a principle that
God does not chasten except to amend, and that the sole end of His greatest anger is the amelioration of the guilty. As the doctor uses fire and steel in certain deep-seated diseases, so
God does but use the fire of
hell to heal the impenitent sinner. All souls, all impenitent beings that have gone astray, shall, therefore, be restored sooner or later to
God’s friendship. The evolution will be long, incalculably long in some cases, but a time will come when
God shall be all in all. Death, the last enemy, shall be destroyed, the body shall be made spiritual, the world of matter shall be transformed, and there shall be, in the universe, only peace and unity. (emphasis mine)
I wanted to post it here, because it is a good explanation of the doctrine. This really makes sense, I must say. It shows that God is responsible with His creation in that He will refine and purify His creation and restore it to Himself.
The whole article can be found here:
newadvent.org/cathen/01599a.htm