What does Acts 2:19 mean?
Peter is using the prophecy found in Joel 2:28–32 to explain why a group of Jesus-following Galileans have spontaneously become multi-lingual (Acts 2:1–13). Their sudden skill with obscure human languages is a sign that they have received the Holy Spirit, that they belong to God, and He is allowing them to prophecy (Acts 2:17–18).The part of Joel's prophecy that Peter covers in Acts 2:19–20 is an explanation of what will happen to those who do not repent of their sins or turn back to God. It isn't clear that this prophecy is fulfilled in the time of the early church; the blood, fire, and smoke might signify the destruction of Jerusalem and the burning of the temple in AD 70. Prophecy, both in the Old and New Testaments, usually only deals with God's plan for the Jews. The church age, part of the "times of the Gentiles" (Luke 21:24), is "foreshortened." That is, a prophet may be talking about the Babylonian exile of Judah in one breath and the tribulation in another.
That seems to be happening here as the phenomena are mentioned by John in the book of Revelation. The stars will fall to the earth, the sky will roll away like a scroll, and the islands will move (Revelation 6:13–14). Later, hail and fire will fall from the sky, and a third of the earth will burn (Revelation 8:7). A third of the sun, moon, and stars will be darkened (Revelation 8:12). Later still, a third of mankind will die in fire and smoke (Revelation 9:18). Beyond these specific fulfillments, "wonders in the heavens" and "signs on the earth" can be taken to mean God will do mighty things all over creation.
The book of Revelation is one of the last books in the Bible to be written; John writes it after all the other apostles and most of Peter's audience has died. Neither Peter nor his listeners understand the specifics of the end times John will witness and write about. As far as Peter's audience is concerned, the call to repentance is immediate, and they respond immediately (Acts 2:37–41). Joel's prophecy stands, however. Whoever repents and follows God before the rapture will escape the judgment of God's wrath.
