The preceding promises foreshadowed even greater deliverance and blessing for the Israelites in their far distant future. The clues to a leap to the distant future in the prophet's perspective are the words "after this"(2:28), "in those days"(2:29), "the great and awesome day of the Lord"(2:31; cf. 2:11), "in those days and at that time"(3:1), and "in that day"(3:18).
2:28-29 After this, namely, after the deliverance from the northern invader just described, God promised to pour out His Spirit on all mankind without gender, age, class, or position distinction.29In Old Testament times God gave His Spirit only to select individuals (cf. Num. 11:24-29; 1 Sam. 10:10-11; 19:20-24), but in the future everyone (i.e., all believers) would prophesy and receive revelations from the Lord. Visions and dreams were God's customary ways of giving special revelations to people in Old Testament times (cf. Num. 12:6). Normally the absence of prophetic revelation indicated sin and divine judgment, but the presence of such revelation reflected divine blessing (cf. 1 Sam. 3:1). So a universal bestowal of the Spirit indicates a time of unprecedented divine blessing.
2:30-31 The Lord also promised awesome displays of celestial phenomena before this great and terrible day of the Lord arrived. Awe-inspiring miracles would occur in the sky as well as on the earth. The appearance of blood, fire, and columns of smoke suggests warfare, with God's hand at work behind the scenes (cf. Exod. 19:9, 16-18; Rev. 6:12-17). The sun would become dark and the moon would turn red. These are probably descriptions of how these heavenly bodies will look (language of appearance), not what will become of them, in view of other similar descriptions (e.g., vv. 10, 15; 3:15; Jer. 4:23-24; Ezek. 32:6-8; Amos 5:18-20; 8:9; Zeph. 1:15; Rev. 6:12-13). These signs will precede the great and awesome day of the Lord still future (cf. Matt. 24:29-31; Mark 13:24-27; Luke 21:25-28).
2:32 The promise continued that whoever would call on the name of Yahweh would be delivered. The day of the Lord described earlier in this chapter involved God judging the enemies of His people, and this eschatological day of the Lord also involves divine judgment. Therefore the deliverance in view must be from divine judgment (cf. Rom. 11:26). Specifically there will be people on Mt. Zion and in Jerusalem who escape, even among the survivors of previous distresses whom Yahweh has elected for deliverance (cf. Isa. 51:2; Zech. 13:8).
The Apostle Paul quoted this verse and applied it to spiritual salvation (Rom. 10:13). His usage does not fulfill what God promised here, namely, physical deliverance before the coming day of the Lord. Paul meant that just as God will deliver all who call on Him in that future day of the Lord, so He will deliver all who call on Him for salvation from sin. They will avoid the terrible day in which all unbelievers will be condemned by their Judge (Rev. 20:11-15).
The Apostle Peter also quoted this passage (vv. 28-32) in his Pentecost sermon (Acts 2:14-36). He said that what the people of Jerusalem were witnessing, which they mistook for drunkenness, was what Joel had spoken of (Acts 2:16-21; cf. Acts 10:45). Many interpreters believe that Peter meant that Joel's prophecy was fulfilled on the day of Pentecost. This can hardly be what he meant, however, because much of what Joel predicted in this passage did not occur on the day of Pentecost. The day of Pentecost was not the day of the Lord.
Another interpretation of Peter's meaning is that part of what Joel predicted was fulfilled on Pentecost, and the rest awaits fulfillment in the future day of the Lord. The problem with this view is that the promises of the outpouring of the Spirit and the other miracles are so intertwined that separating them by thousands of years seems unnatural. Moreover, Peter quoted the whole passage in Joel, not just the promise of the Spirit's outpouring.
A third possible interpretation is that Peter meant that what happened on Pentecost was similar to what Joel had prophesied God would do in the future day of the Lord. He drew a comparison and pointed out an analogy, but he did not claim fulfillment. This view sees the entire fulfillment of Joel's prophecy in the eschatological future. This view makes the most sense to me. The outpouring on the day of Pentecost was a foreview of what the Lord will do in the future (cf. Gal. 3:28).30
"Peter quoted this passage in Acts 2 because (a) it related to the outpouring of God's Spirit (2:4, 15-16), (b) it stressed his theme of repentance (2:21, 37-39), and (c) it fit with his understanding that the Jews were about to enter the Day of the Lord, leading up to the return of Israel's Messiah, Jesus (1:6-8; 2:36; 3:19-21)."31
The day of the Lord in view here begins with the Tribulation (cf. Dan. 9:24-27; Rev. 6-18), continues through the return of Christ and the Millennium (cf. Rev. 19-20), and culminates in the eternal state (cf. 2 Pet. 3:10-13; Rev. 21-22). The signs in view picture what the Book of Revelation describes further as occurring in the Tribulation, and the pouring out of the Spirit will occur in the Millennium. Then all believers will possess the Spirit and will have the ability to receive fresh revelations from the Lord. Forgiveness of sins and the indwelling of the Holy Spirit are two of four great blessings of the New Covenant (Jer. 31:31-34; Ezek. 36:24-30).
God's judgment on unbelievers would accompany the spiritual renewal and deliverance of His own in the future day of the Lord. As God promised to wipe out the locusts for despoiling Judah, now He promised to do the same to the nations that had despoiled Judah (cf. Zeph. 3:8; Ezek. 38-39; Matt. 25:31-46).
3:18 Joel continued to describe the future day of the Lord, but now he passed from the judgments of the Tribulation to the blessings of the Millennium. The mountains of Israel would be so full of grapevines that they could be described as dripping with wine. There will be so many milk-yielding animals feeding on the luxuriant hills that the hills could be said to flow with milk. Instead of the wadis that have water in them only a few days each year, the steams of Judah would flow with abundant, life-giving water. All these descriptions recall conditions in paradise (cf. 1:5, 18, 20). A spring will flow out from the millennial temple that will water the valley of acacia trees, evidently between Jerusalem and the Dead Sea (cf. Ezek. 47:1-12; Zech. 14:8). This will also be a visual reminder that Yahweh is the source of all provisions and fruitfulness.
3:19-20 Egypt and Edom, probably representative of Israel's enemies, will become deserts because they shed innocent blood, presumably the blood of God's people. But Judah and Jerusalem would be full of people for all generations to come (cf. Ezek. 37:25; Amos 9:15; Zech. 14:11).
3:21 God's final promise through Joel was that He would avenge the blood shed by these enemies of Israel, which He had not yet avenged in the prophet's day. He promised to do this because He dwelt in Zion, that is, He had a special covenant relationship with Israel (cf. Ezek. 43:1-12; Zech. 2:10-13).
The prophecy of Joel unfolds in chronological sequence. It begins with reference to a severe locust invasion that came as a judgment on the Judahites for their covenant unfaithfulness to Yahweh (1:2-20). Even though it is impossible to date this plague, it happened in the recent past from Joel's perspective. The Lord used this severe judgment to call His people, through His prophet, to anticipate an even worse devastation coming in the near future, not from insects but from foreign invaders. He called on the Jews to repent and promised that if they did He would forgive them and spare them from this invasion. This would be a day of deliverance in which they would learn that He was at work for them. Yet another similar day was coming farther in the future in which they would again experience an invasion by foreigners who hated them. Nevertheless Yahweh promised to deliver them in that day and to restore them to unprecedented blessing because He was their covenant God.