By Dr. Michael J. Vlach
Zechariah 14:1–9 revealed the timing of the kingdom of God. God's kingdom comes in the context of a multi-national siege of Jerusalem that is foiled by the Lord's intervention on behalf of Jerusalem and the people of Israel. At that time, "The Lord will be king over all the earth" (v. 9).
Verse 10–21 reveal important details about the nature of the kingdom. The kingdom involves even more changes to Jerusalem as verse 10 indicates:
All the land will be changed into a plain from Geba to Rimmon south of Jerusalem; but Jerusalem will rise and remain on its site from Benjamin's Gate as far as the place of the First Gate to the Corner Gate, and from the Tower of Hananel to the king's wine presses.
Verse 11 also shows that "Jerusalem will dwell in security."
Verses 12–15 describe what will happen to those who previously waged war against Jerusalem. Destruction, panic, and plague befall the enemies of Israel.
Now this will be the plague with which the LORD will strike all the peoples who have gone to war against Jerusalem; their flesh will rot while they stand on their feet, and their eyes will rot in their sockets, and their tongue will rot in their mouth. It will come about in that day that a great panic from the LORD will fall on them; and they will seize one another's hand, and the hand of one will be lifted against the hand of another. Judah also will fight at Jerusalem; and the wealth of all the surrounding nations will be gathered, gold and silver and garments in great abundance. So also like this plague will be the plague on the horse, the mule, the camel, the donkey and all the cattle that will be in those camps.
Verses 16–19 then detail the relationship of the nations to the kingdom:
Then it will come about that any who are left of all the nations that went against Jerusalem will go up from year to year to worship the King, the LORD of hosts, and to celebrate the Feast of Booths. And it will be that whichever of the families of the earth does not go up to Jerusalem to worship the King, the LORD of hosts, there will be no rain on them. If the family of Egypt does not go up or enter, then no rain will fall on them; it will be the plague with which the LORD smites the nations who do not go up to celebrate the Feast of Booths. This will be the punishment of Egypt, and the punishment of all the nations who do not go up to celebrate the Feast of Booths.
Several points from this section are worthy of note.
First, there are some people from the nations that survive the judgments of the Lord (v. 16).
Second, those who survive the judgments of the Lord from among the nations will go to Jerusalem to worship the King. The nations must now come to worship the King in person as He rules from Jerusalem, His capital city. This shows that Jerusalem as a city and Israel as a nation have future significance.
Third, survivors from the nations will celebrate the Feast of Booths. This feast was one of three times on Israel's calendar when God's people were to present themselves at the sanctuary (see Lev. 23:34–44). The purpose of the feast was to celebrate the Lord's provision for Israel during their wilderness journey.
So how will an Israelite feast relate to the nations when the Lord rules upon the earth? Eugene Merrill points out that "there is evidence that this was an occasion for some kind of recognition of the king as YHWH's son and representative." Thus, "For the nations to observe the Feast of Tabernacles was for them to come in submission before the King of all the earth and render to Him their expressions of subservience."  In short, the Feast of Booths will be an opportunity for the nations of the earth, as national entities, to express their allegiance to the Lord.
Fourth, nations that do not observe the Feast of Booths will experience negative consequences. The Lord will smite the nations that disobey. Egypt for example, who appears as a representative of the nations at this time, will not experience rainfall. This shows that during this phase of the Lord's reign over the earth, disobedience is still possible for some and that the Lord's righteous reign involves punishment on occasion.
Verses 20–21 indicate that everything during this period will be holy to the Lord, even those things usually considered mundane:
In that day there will be inscribed on the bells of the horses, "HOLY TO THE LORD." And the cooking pots in the LORD'S house will be like the bowls before the altar. Every cooking pot in Jerusalem and in Judah will be holy to the LORD of hosts; and all who sacrifice will come and take of them and boil in them. And there will no longer be a Canaanite in the house of the LORD of hosts in that day.
In sum, this section reveals that the Lord will reign from Jerusalem over the nations. The nations must show their allegiance by observing the Feast of Booths. Those nations that do not obey the Lord will experience negative consequences, including the withholding of blessings.
 Eugene H. Merrill, Haggai, Zechariah, Malachi: An Exegetical Commentary (Chicago: Moody Press, 1994), 362–63.