You will closely note, Zechariah 14:16 & Isaiah 4:3-4 are "Parallel" readings of the same event, as Isaiah gives a clear account of those who are left, those who are found in the book of life, the final judgement has passed, eternity has begun "After" The Day Of The Lord
You will closely note in Isaiah 4:4 below, Jerusalem will be purged by the spirit of (Burning)
Zechariah 14:12KJV
12 And this shall be the plague wherewith the Lord will smite all the people that have fought against Jerusalem; Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.
Only The Righteous Are Left, The Book Of Life "Was" Opened (Every One That Is Written Among The Living)
Zechariah 14:16KJV
16 And it shall come to pass, that every one that is left of all the nations which came against Jerusalem shall even go up from year to year to worship the King, the Lord of hosts, and to keep the feast of tabernacles.
Isaiah 4:3-4KJV
3 And it shall come to pass, that he that is left in Zion, and he that remaineth in Jerusalem, shall be called holy, even every one that is written among the living in Jerusalem:
4 When the Lord shall have washed away the filth of the daughters of Zion, and shall have purged the blood of Jerusalem from the midst thereof by the spirit of judgment, and by the spirit of burning.
You will closely note in Isaiah 4:4 below, Jerusalem will be purged by the spirit of (Burning)
Zechariah 14:12KJV
12 And this shall be the plague wherewith the Lord will smite all the people that have fought against Jerusalem; Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.
Only The Righteous Are Left, The Book Of Life "Was" Opened (Every One That Is Written Among The Living)
Zechariah 14:16KJV
16 And it shall come to pass, that every one that is left of all the nations which came against Jerusalem shall even go up from year to year to worship the King, the Lord of hosts, and to keep the feast of tabernacles.
Isaiah 4:3-4KJV
3 And it shall come to pass, that he that is left in Zion, and he that remaineth in Jerusalem, shall be called holy, even every one that is written among the living in Jerusalem:
4 When the Lord shall have washed away the filth of the daughters of Zion, and shall have purged the blood of Jerusalem from the midst thereof by the spirit of judgment, and by the spirit of burning.