This expression is found in Acts 3:21 and refers to all the things which the prophets of Israel had prophecied concerning the nation’s blessing under its Messiah in the world to come. It coincides with the Lord’s statement about Elijah’s coming and restoring “all things” (Matt. 17:11).
The statement, “the restitution of all things,” has been erroneously used to support the false doctrine of universalism—the eventual salvation of all God’s creatures, so that none end up in Hell. However, Peter qualified his remark concerning the restitution of all things by adding, “Which God hath spoken by the mouth of all His holy prophets.” Thus, the “all things” that he was referring to were those things which the prophets of Israel had prophecied—namely, the restoration of the nation and its blessing under its Messiah.