By rejecting their Messiah, the Jews broke their covenant with God. Yet according to the prophetic vision of the Apostle Paul, a time will someday come.
The Jewish people, in its mass as a nation, will turn to faith in the Messiah, Jesus of Nazareth, and God will have mercy on His people.
God foretold this conversion of Israel through His prophets, as the Apostle Paul indicates in the mentioned passage, citing the most important of such prophecies.
This time and this event are what the Apostle Peter calls here the restoration of all things, which God spoke by the mouth of His holy prophets from the age.
The apostle contemplates this time as a time before the end of the world. After this, God will send the Messiah appointed for them.
That is, the second coming of the Lord Jesus will follow. The apostle says that God speaks of this by the mouth of all His prophets from the age.
He speaks in the same sense as above, in verse 18, where he said that all the prophets foretold the sufferings of Christ.
Thus the verses under consideration characterize the whole time of Christ's kingdom on earth until His very second coming.
It is a time of spiritual refreshing for believing Jews, as also for Gentiles. Toward the end it is a time of restoring true relations between God and the chosen people.
Then the second glorious coming of the Lord Jesus to earth will follow, for the final judgment of the whole world.
To understand the force of this apostolic exhortation to repentance and conversion of the Jews, the apostle's hearers, to Christ, one must remember something.
The apostles, while urging believers toward a virtuous life, often impressed upon them the need to keep Christ's second coming near in thought.
The day of this coming is unknown, rests in the will of God, and will come like a thief in the night (1 Thess 4:15 and following; 1 Thess 5:1 and following; 1 Cor 7:29 and following, and parallels).
The general "meaning of this text is that much of what was foretold by the prophets has not yet been fulfilled."
"It is being fulfilled and will be fulfilled until the end of the world. For Christ, who ascended into the heavens, will remain there until the end of the world."
"He will come with power when, at last, everything foretold by the prophets is fulfilled" (Theophylact).