I will also gather all the nations, and will bring them down into the valley of Jehoshaphat, and I will enter into judgment with them there on account of my people and mine inheritance, Israel, whom they have scattered among the nations: and they have parted my land;
Joel 3:1 For behold, in those days, and in that time, when I shall turn again the captivity of Judah and Jerusalem,
Joel 3:2 I will also gather all the nations, and will bring them down into the valley of Jehoshaphat, and I will enter into judgment with them there on account of my people and mine inheritance, Israel, whom they have scattered among the nations: and they have parted my land;
Joel 3:3 and they have cast lots for my people, and have given a boy for a harlot, and sold a girl for wine, and have drunk [it].
Joel 3:4 Yea also, what have ye to do with me, O Tyre and Zidon, and all the districts of Philistia? Will ye render me a recompence? But if ye recompense me, swiftly [and] speedily will I bring your recompence upon your own head;
The verse centers on "gather", "nations", "bring", "down", "valley", "jehoshaphat", "enter", and "judgment". It is saying that the verse draws attention to "gather" and "nations", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "For behold in those days and in..." into verse 3's "and they have cast lots for my...", so "gather" and "nations" belong inside that flow. In Joel context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "gather" and "nations" with trust shaped by these words, not by a vague optimism outside the passage.