Shared ground
Joel 3:12–13 presents a staged scene: the nations are summoned to gather at “the valley of Jehoshaphat,” and the LORD announces that he will sit there to judge the surrounding nations. That much is explicit in the text (a commanded gathering, a named place, and the LORD’s stated purpose to judge).
The next images—sickle, ripe harvest, full winepress, overflowing vats—are also explicit, but they function as metaphors. The passage itself explains the moral basis for the action: “for their wickedness is great.” The imagery communicates that judgment is due and imminent because the nations’ evil has reached an overflowing “fullness.”
Where interpretation differs
Some readers take “the valley of Jehoshaphat” as a specific future (or historical) geographic location near Jerusalem where the nations will literally assemble. Others understand the name mainly as a symbolic way of saying “the place where the LORD judges,” without requiring a map-identifiable valley.
A second, smaller question is who is being addressed by “Put in the sickle” and “Come, tread.” Some take these commands as directed to God’s agents (whether angelic or human) carrying out judgment. Others hear them as part of the prophetic announcement itself—vivid, dramatic speech that describes what will happen without identifying the agents.
Why the disagreement exists
The passage uses a concrete place-name (“valley of Jehoshaphat”) but does not provide geographic details, and Joel continues with strongly figurative agricultural language. Because the text combines “real-sounding” location language with metaphor, readers weigh those features differently.
What this passage clearly contributes
This text contributes a focused claim about divine judgment on the nations: (1) the LORD initiates and controls the gathering; (2) judgment is depicted as a decisive session where the LORD “sits” to judge; and (3) the harvest/winepress pictures underscore readiness and certainty—judgment is not arbitrary but presented as responding to “great” wickedness. Inference beyond that (exact geography, the identity of the “reapers,” or a detailed end-times timeline) goes beyond what these two verses state directly. See also the larger “Day of the LORD” frame in Joel 3:14–16.