In theology, apokatastasis (Greek: ἀποκατάστασις, /æpoʊkəˈtæstəsɪs/, also spelled apocatastasis) is the restoration of creation to a condition of perfection.[1][2] In Christianity, the term refers to a form of Christian universalism, often associated with Origen, that includes the ultimate salvation of everyone—including the damned and the Devil.[3][4][5] The New Testament (Acts 3:21) speaks of the "apokatastasis of all things," although this passage is not usually understood to teach universal salvation.[6] The dogmatic status of apokatastasis is disputed,[7] and some orthodox fathers such as Gregory of Nyssa taught apokatastasis and were never condemned.[8]
Apocatastasis. The Greek name (ἀποκατάστασις) for the doctrine that ultimately all free moral creatures—angels, men, and devils—will share in the grace of salvation; cf. article "Universalism".
[T]heories of the apocatastasis usually involve the expectation that in the end all, including the devil, will be saved.
[Apocatastasis is] the idea that all things will be ultimately reconciled to God through Christ—including the damned in hell and even Satan and his demons.
The usual view taken of Peter's use of the apokatastasis of "all things" is that it refers to the restoration of the Kingdom of Israel and/or the Garden of Eden and not "all things that ever existed."