The harvest of Revelation 14:14–20 comes in the context of the proclamation of the eternal gospel
of Revelation 14:6–11 and its rejection by the inhabitants of the earth. Given the holiness of the Lord God, this rejection must result in judgment (Revelation 14:7). The prophets of the Old Testament had already used the image of what happens to grapes in a winepress to illustrate what God’s judgment is like (Isaiah 63:3; Joel 3:13). That same image of crushing, breaking, pulverizing now appears in relation to the last judgment. God’s wrath is devastatingly destructive. Note that this reference to a winepress as a picture of God’s wrath connects the work of this third angel to the work of the last angel of the previous threesome (Revelation 14:9–11), where that angel declared that all who worshipped the beast would have to drink the wine of God’s wrath.
Further, the imagery of the winepress as picture of God’s wrath explains why the harvest of the earth is now described in terms of grapes
(as opposed to grain).
19 So the angel swung his sickle across the earth and gathered the grape harvest of the earth and threw it into the great winepress of the wrath of God.