Commentary - Isaiah 27:12-13

Bird's-eye view

In these closing verses of Isaiah 27, the prophet shifts from judgment to a glorious promise of restoration and ingathering. Having described the Lord’s victory over Leviathan and His chastening of His people, Isaiah now paints a picture of a great, worldwide harvest. This is not merely a political restoration of ethnic Jews to a parcel of land in the Middle East. This is a picture of the gospel harvest, a central theme of God’s redemptive purpose throughout history. Yahweh Himself is the great harvester, meticulously gathering His scattered people, one by one, from all the nations of their exile. The passage climaxes with the sound of a great trumpet, a familiar biblical symbol for a divine summons, calling the lost and the perishing to return, not just to a geographical location, but to a place of true worship, the holy mountain of God in Jerusalem. This is a profoundly Christological and ecclesiological prophecy, pointing to the work of Christ in building His Church from every tribe, tongue, and nation.

This is postmillennial language. It describes the steady, inexorable advance of the kingdom of God in history. The Lord is not wringing His hands over a disobedient world; He is actively threshing the nations and gathering His own. The trumpet call is the gospel itself, preached with power, and the result is a great assembly of worshippers coming to Zion, which is the Church of the living God. This is not about a future panicked evacuation, but about a present and future glorious gathering.

Outline

Context In Isaiah

Isaiah 24 through 27 form a distinct unit often called the "Little Apocalypse." This section describes a worldwide judgment on the "city of chaos" (the world system in rebellion against God) and the ultimate triumph and celebration of God's people in the "city of God." Chapter 27 continues this theme, beginning with God's victory over Leviathan (a symbol of cosmic evil and rebellious nations) and describing God's careful pruning and preservation of His vineyard, Israel. Our text, verses 12-13, serves as the grand finale to this section. After all the upheaval, judgment, and chastisement, the final word is one of sovereign grace and restoration. God is not finished with His people. The purpose of His discipline was not destruction, but purification and, ultimately, salvation. This passage therefore provides the positive counterpart to the judgments described earlier, showing that God's ultimate intention is to gather a redeemed people for Himself to worship Him in His holy city.

Clause-by-Clause Commentary

v. 12 And it will be in that day,

The phrase "in that day" is a standard prophetic marker, and it points to a significant time of God’s intervention in history. It doesn't refer to a single 24 hour period, but rather to an era, a decisive age. In the Old Testament, it often pointed to a coming judgment and restoration for Israel, but its ultimate fulfillment is in the age of the Messiah. This is the gospel age, the time between the first and second advents of Christ. This is the day of salvation, the day when the realities Isaiah is about to describe are set in motion by the death and resurrection of Jesus Christ.

that Yahweh will start His threshing from the flowing stream of the River to the brook of Egypt,

Here we see God as the active agent. Yahweh Himself is the one who threshes. Threshing is an agricultural metaphor for separating the grain from the chaff, the valuable from the worthless. In the context of judgment, it can mean separating the wicked from the righteous. But here, the emphasis is positive. It is a harvest. God is beating out the grain, His people, from the places where they have been scattered. The geographical boundaries, from the Euphrates River to the Wadi el-Arish (the brook of Egypt), define the ideal borders of the land promised to Abraham. In Isaiah’s time, this represented the whole known world from Israel's perspective. The scope is comprehensive. God's harvest operation is not a small, localized affair. It is a vast, international work of reclamation. This is a picture of the Great Commission. The gospel goes out to all the nations, and God threshes His people out of every pagan system.

and you will be gathered up one by one, O sons of Israel.

This is a beautiful and tender phrase. God’s gathering is not an impersonal mass movement. It is personal and individual. He knows His sheep by name. He gathers them "one by one." This speaks to the doctrine of effectual calling. The gospel trumpet may sound for all, but the Spirit of God applies that call to each of His elect individually, drawing them to faith in Christ. And who are the "sons of Israel"? In the new covenant, Israel is not defined by ethnic lineage but by faith in the true Israel, Jesus Christ. As Paul says, not all Israel is Israel (Romans 9:6). The true sons of Israel are those, Jew and Gentile, who are united to Christ by faith. They are the children of the promise. So this is a promise for the Church, the commonwealth of Israel, being gathered from all the corners of the earth.

v. 13 And it will be in that day, that a great trumpet will be blown,

Again, "in that day," the gospel age. The blowing of a great trumpet in Scripture is always a significant event. It was used to assemble the congregation of Israel, to announce the beginning of a festival, to sound a call to war, or to herald the coronation of a king. Here, it is a divine summons. This is the powerful, authoritative call of the gospel of the kingdom. When Christ ascended, He established His kingdom, and the trumpet blast that announces this reality is the preaching of the Word. Think of the seventh trumpet in Revelation, when the kingdom of this world becomes the kingdom of our Lord and of His Christ. This is not a secret rapture whistle, but a public, world-shaking announcement that Jesus is Lord, and it is a call for His people to assemble.

and those who were perishing in the land of Assyria and who were banished in the land of Egypt will come

Assyria and Egypt were the two great superpowers that oppressed and scattered Israel. They represent all the hostile world systems where God’s people find themselves exiled, perishing, and lost. They are emblems of the kingdom of darkness. But the gospel trumpet reaches even there. It finds those on the brink of destruction, the outcasts, the banished. This is a picture of our state outside of Christ. We are perishing in our sins, banished from the presence of God. But the gospel call is powerful enough to rescue us from the strongest fortresses of the enemy. And the result is not that they might come, but that they will come. The call is effective. When God blows His trumpet, His people respond.

and worship Yahweh in the holy mountain at Jerusalem.

This is the goal of the entire operation. God doesn't just save us from something; He saves us for something. And that something is worship. The gathered exiles come to worship Yahweh. And where do they do it? "In the holy mountain at Jerusalem." The New Testament is clear that the physical city of Jerusalem and its mountain are types and shadows. The writer to the Hebrews tells us that we have come to Mount Zion, the heavenly Jerusalem (Heb. 12:22). This is the Church. When we gather for worship on the Lord's Day, we are ascending to the true holy mountain. This prophecy is fulfilled every time sinners are converted by the gospel and are brought into the worshipping community of the saints. The gathering is not to a place, but to a Person, Jesus Christ, and to His body, the Church, which is the true temple and the holy city of God.

Application

First, we must have a robust confidence in the power of the gospel. The great trumpet is blowing. God is not failing in His purposes. He is, right now, threshing the nations and gathering His people one by one. Our task is to be faithful in proclaiming the message, knowing that it is the power of God for salvation. We should not be discouraged by the apparent strength of "Assyria" or "Egypt." God's trumpet is louder than their noise.

Second, we must understand the personal nature of salvation. God is gathering His people "one by one." This should banish all forms of impersonal religion. Your relationship with God through Christ is a personal one. He sought you out individually. This should lead to profound gratitude and a desire to live a life worthy of such a specific, detailed, and loving calling.

Finally, we must see that the central activity of the gathered people of God is worship. The whole point of the harvest and the trumpet call is to bring a people to the holy mountain to worship Yahweh. This is why our corporate worship on the Lord's Day is not an optional extra for the keen Christian. It is the central, defining act of the people of God. It is where we ascend to the heavenly Jerusalem. It is the fulfillment of Isaiah's prophecy. Therefore, we should come to worship with joy, reverence, and a sense of our high calling as those who were once perishing but have now been brought near by the blood of Christ to worship the living God.