What will happen on that Day?

 Read Zechariah 12.

This chapter may be the most compact prophecy concerning the Jews in the entire Bible.  It is "the word of the LORD concerning Israel."  The trigger phrase is "on that day," which is repeated throughout this oracle, and refers to those future events surrounding the second coming of Christ.

Overarching the prophecy is the reminder that God is not only the Creator of all things but He is also the Almighty Controller.  And, it is personal.  He even "formed the spirit of man within him" (v.1).  Therefore, the LORD's ability to raise up and put down entire nations is without question for the Omnipotent God of the Bible.  As He is Omniscient, He can accurately communicate in advance here what will take place then.

1. All nations of the earth will gather against Jerusalem. (vv.2-9)
As an example, one can imagine what would happen if suddenly Israel took over the Dome of the Rock, destroyed it, and began building a new Temple.  Or, if Israel began reclaiming all the territory promised to Abraham and his descendants as listed in Genesis.  Whatever the cause, the nations of the world will one day unite in an attempt to fight against Israel and to destroy Jerusalem.  This is the battle of Armageddon.

However, the collective military might of the world will utterly fail.  It will not be because of Israel's military superiority or cunning.  "The LORD will give salvation to the tents of Judah..." (v.7).  The Jews will be supernaturally empowered to fight.  "...the feeblest among them on that day shall be like David" (v.8).  God states, "...I will seek to destroy all the nations that come against Jerusalem" (v.9).  Jesus will appear with His heavenly armies and crush all the enemy forces (Revelation 19:11-16).

2. Israel will experience a period of deep repentance. (vv.10-14)
When Jesus reveals Himself in the heavens, the Jews will "look on me, on him whom they have pierced."  The weeping and mourning will be traumatic for every person as they realized that Jesus really is the Messiah.

3. Israel will be cleansed from all sin. (13:1)
The Jews will welcome the forgiveness, paid for by Christ on the cross.  That fountain of His shed blood alone has the power to "cleanse us from all unrighteousness" (1 John 1:9).

William Cowper penned the old and graphic hymn.
"There is a fountain filled with blood drawn from Immanuel's veins;
And sinners, plunged beneath that flood, lose all their guilty stains."