The “day of the Lord” is the dominant theme of the book of Joel. Both the nations (Joel 3:2–3) and Israel (Joel 1:15; 2:1–2) experience this judgment. However, for the repentant community, the “day” also holds out the hope of restoration (Joel 2:12–14). Ultimately, the Lord’s covenant faithfulness is expressed in his promises of abundance and protection (2:23–26; 3:1), which evidence his dwelling in the midst of his people (Joel 2:27; 3:17, 21). This is epitomized in the great promise of “my Spirit” that would be poured out on “all flesh” (Joel 2:28, 29; cf. Acts 2:17–21).
1. Day of the Lord. This is the major theme of Joel. The exact expression, yom yhwh (Hb., “day of the Lord”), is found five times in Joel (Joel 1:15; 2:1, 11, 31; 3:14) and 13 times in seven other prophetic books (Isa. 13:6, 9; Jer. 46:10; Ezek. 13:5; 30:3; Amos 5:18–20; Obad. 15; Zeph. 1:7, 14; Mal. 4:5; see ESV Study Bible note on Amos 5:18–20). Other ways of referring to the “day” found throughout prophetic literature (e.g., “a day,” “those days,” “that day”) are used by Joel as well (Joel 2:2; 3:1, 18). Within Joel, the “day” refers not only to a final day of judgment upon the nations (Joel 3:2) but also to God’s ongoing judgment of Israel, both past and future (Joel 1:15; 2:2, 11), and instances of his intervention between Israel and the nations (Joel 3:1–2, 12, 14, 16). In each case, the “day of the Lord” indicates a time when the presence of the Lord brings judgment and/or deliverance and blessing, depending on the circumstances (see ESV Study Bible note on Joel 1:15). Therefore, although the “day” heralds destruction for the nations, it also functions as a time of salvation for God’s people; the Lord remains a refuge amid the chaos of judgment (Joel 3:15–16).
2. Repentance. If the whole community would cry out to the Lord (Joel 1:13–20) and look to him—not merely with external actions but in sincerity with their whole persons (Joel 2:12–13)—then judgment may be averted. However, the Lord is not bound by the acts of the community (Joel 2:14); it is his prerogative to send or withhold the destruction by the locusts (Joel 1:15), just as the army is his to command (Joel 2:11).
3. The Lord in their midst. It is, of course, crucial that the people have a living faith and repentance; however, the reason the Lord will turn from judgment to blessing is to express his covenant-keeping character (Joel 2:13, 18–26; 3:18). His promise to dwell in the midst of his people is prominent not only in Joel (Joel 2:27; 3:17, 21) but also throughout the OT (Num. 35:34; Deut. 6:15; 7:21; Isa. 12:6; Hos. 11:9; Zeph. 3:15, 17; Hag. 2:5; Zech. 2:10–11; 8:3). God’s restoration of what the locusts have destroyed (Joel 2:27) and his protection of Israel as the cosmos crumbles (Joel 3:16–17) both have the same goal: knowledge of his presence. This theme concludes the book (Joel 3:21), highlighting its importance for Joel.
4. These themes—the day of the Lord, repentance, and God dwelling amid his people—converge in the promise of the future outpouring of the Spirit (Joel 2:28–32). This outpouring is associated with the day of the Lord (Joel 2:31) in both its judgmental (Joel 2:30–31; cf. Joel 2:10; 3:15) and its saving (Joel 2:32) manifestations. It is related to repentance in that those who are saved are those who call “on the name of the Lord” (Joel 2:32). Finally, the giving of the Spirit, crossing all boundaries of gender, generation, social class, or nationality (Joel 2:28–29), is the ultimate evidence of God “in the midst of them” (Isa. 63:11; see Hag. 2:5).