Many call this last high day of the year, "The Last Great Day," because of John's words:

John 7:37 (KJS)  In the last day, that great [day] of the feast, {Yahshua} stood and cried, saying, If any man thirst, let him come unto me, and drink.

The NIV refers to it as the "Closing Assembly." Scripture does not actually give the day a specific name.
In Leviticus it says:

Lev 23:36 (KJS) Seven days ye shall offer an offering made by fire unto {[Yahweh]}: on the eighth day shall be a {set-apart assembly}unto you; and ye shall offer an offering made by fire unto {[Yahweh]}: it [is] a solemn assembly; [and] ye shall do no servile work [therein].

Scripture simply says, "on the eighth day."  This would be the 22nd of Ethanim.  It is described as a solemn assembly, in Hebrew () "ats-aw-raw," which means a "restrained assembly."  Although the Hebrew people, then, probably didn’t know why the assembly was to be solemn, we now know because of John’s writing of Revelation that this day represents the Judgment day at the White Throne of chapter 20.  Many will not make it into the kingdom; according to Matthew 7:14, it will be few.

Matt 7:13 (NIV) "Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.
14 But small is the gate and narrow the road that leads to life, and only a few find it.
This is, of course, sad even though we know Yahweh is just.  Thus, the assembly is solemn reflecting on mankind in general.  That last day will certainly not be a day of rejoicing as so many people go to their destruction. It is even referred to as "terrible:"
Joel 2:31 (KJS) The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of [Yahweh] come.
32 And it shall come to pass, [that] whosoever shall call on the name of [Yahweh] shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as [Yahweh] hath said, and in the remnant whom [Yahweh] shall call.

Reve 3:10 (NIV) Since you have kept my command to endure patiently, I will also keep you from the hour of trial that is going to come upon the whole world to test those who live on the earth.
11 I am coming soon. Hold on to what you have, so that no one will take your crown.
12 Him who overcomes I will make a pillar in the temple of [Yahweh]. Never again will he leave it. I will write on him the name of [Yahweh] and the name of the city of [Yahweh], the new Jerusalem, which is coming down out of heaven from [Yahweh]; and I will also write on him my new name.

So, those who have endured and overcome, those whose names are found in the Book of Life on the day of Judgment, will rejoice after that Judgment Day and forever.

A review of events leading up to the White Throne Judgment would be appropriate at this time.

Due to occasional confusion between Second Coming and Final Judgment Scriptures, this review starts at the Second Coming, moves through the 1000 years, and covers the period surrounding the White Throne Judgment.

Note how the descriptions of the coming by different authors, fill in the pieces of the picture:

Matt 24:27 (KJS) For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be.
Matt 24:30 (KJS) And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
31 And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.

Zech 14:4 (NIV) On that day his feet will stand on the Mount of Olives, east of Jerusalem, and the Mount of Olives will be split in two from east to west, forming a great valley, with half of the mountain moving north and half moving south.
5... Then [Yahweh] {Son} my [Mighty One] {Eloha} will come, and all the [Set-apart] ones with him.
6 On that day there will be no light, no cold or frost. [So a time of year when frost is expected]
7 It will be a unique day, without daytime or nighttime--a day known to [Yahweh]. When evening comes, there will be light.
8 On that day ["during those days" - the 1000 years] living water will flow out from Jerusalem, half to the eastern sea and half to the western sea, in summer and in winter.
9 [Yahweh] will be king over the whole earth. On that day there will be one [Yahweh], and his name the only name.
10 The whole land, from Geba to Rimmon, south of Jerusalem, will become like the Arabah [desert]. But Jerusalem will be raised up and remain in its place, from the Benjamin Gate to the site of the First Gate, to the Corner Gate, and from the Tower of Hananel to the royal winepresses.
11 It will be inhabited; never again will it be destroyed. Jerusalem will be secure.
12 This is the plague with which [Yahweh] will strike all the nations that fought against Jerusalem: Their flesh will rot while they are still standing on their feet, their eyes will rot in their sockets, and their tongues will rot in their mouths.
13 On that day men will be stricken by [Yahweh] with great panic. Each man will seize the hand of another, and they will attack each other.
14 Judah too will fight at Jerusalem. The wealth of all the surrounding nations will be collected--great quantities of gold and silver and clothing.
15 A similar plague will strike the horses and mules, the camels and donkeys, and all the animals in those camps.
16 Then the survivors from all the nations that have attacked Jerusalem will go up year after year [mortals who continue into the 1000 years that precedes the Judgment] to worship the King, [Yahweh] Almighty, and to celebrate the Feast of Tabernacles {Sukkot}.

1The 4:14 (NIV) …we believe that [Yahweh] will bring with [Yahshua] those who have fallen asleep in him.
15 According to the [Master’s] own word, we tell you that we who are still alive, who are left till the coming of the [Master], will certainly not precede those who have fallen asleep.
16 For the [Master] himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of [Yahweh], and the dead in [Messiah] will rise first. {First Resurrection}
17 After that, we who are still alive and are left will be caught up together with them in the clouds to meet the [Master] in the air…

1Cor 15:22 (NIV) For as in Adam all die, so in [Messiah] all will be made alive. {First Resurrection}
23 But each in his own turn: [Messiah], the firstfruits; then, when he comes, those who belong to him.

The above excerpts describe Messiah’s coming with his "Pure Ones."  It seems to be on or just after Yom Teruah (Trumpets, Shouting, making sounds) with "the trumpet call of Yahweh."  This also appears to be a time of the year with possible frost expected (probably at higher elevations), since  we are told not to expect the normal daytime and nighttime, and then frost is mentioned as being absent.  Also, the verses from Thessalonians and First Corinthians describe the First Resurrection.

When the Messiah comes, he will rule the earth for 1000 years.  From those of the First Resurrection, judges (rulers, priests) will be made to reign with the Messiah.  Since the dead in Messiah will rise (1 The 4:16), those left dead were not part of the body of Messiah.  Perhaps all those risen, and changed, will be these judges (rulers, priests):

Reve 1:5 (KJS) And from [Yahshua Messiah], the faithful witness, the first begotten of the dead, and the prince of the kings of the earth. Unto him that loved us, and washed us from our sins in his own blood,
6 And hath made us kings and priests unto [Yahweh] his Father; to him [be] [esteem] and dominion for ever and ever. Amen.

Revelation chapter 20 gives us much information about this 1000 year period:

Reve 20:4 (NIV) I saw thrones on which were seated those who had been given authority to judge. And I saw the [bodies] of those who had been beheaded because of their testimony for [Yahshua] and because of the word of [Yahweh]. They had not worshipped the beast or his image and had not received his mark on their foreheads or their hands. They came to life and reigned with [Messiah] a thousand years.
5 (The rest of the dead did not come to life until the thousand years were ended.) This is the first resurrection.
This agrees with and ties together the verses from Matthew 24, Zechariah 14, 1 Thessalonians 4, and 1 Corinthians 15.

Satan is also dealt with at the beginning of the 1000 years:

Reve 20:1 (NIV) And I saw an [messenger] coming down out of heaven, having the key to the Abyss and holding in his hand a great chain.
2 He seized the dragon, that ancient serpent, who is the devil [false accuser], or Satan [Ha Satan - the opponent], and bound him for a thousand years.
3 He threw him into the Abyss, and locked and sealed it over him, to keep him from deceiving the nations anymore until the thousand years were ended. After that, he must be set free for a short time.
So Satan has, from the fall of Adam, been deceiving the nations and people of the world.  In fact, he reigns over the world or how could he have made this offer to the Messiah:
Luke 4:5 (NIV) The devil led him up to a high place and showed him in an instant all the kingdoms of the world.
6 And he said to him, "I will give you all their authority and splendor, for it has been given to me, and I can give it to anyone I want to.
7 So if you worship me, it will all be yours."
This is why we see the corruption of our government leaders and the destruction of our constitution and our country.  This is why we now openly here the phrase "New World Order," meaning the establishment of a one world government.  We will probably see the ten horns of Daniel chapter 7 in our lifetime.  Satan is deceiving the nations and people away from Yahweh and toward mysticism and the occult; that which worships him.

Those in the First Resurrection cannot be lost at the Judgment, the White Throne Judgment, on that "terrible" day.

Reve 20:6 (NIV) Blessed {Praised} and holy {set-apart} are those who have part in the first resurrection. The second death has no power over them, but they will be priests of [Yahweh] and of [Messiah] and will reign with him for a thousand years.

It is quite interesting to think what it will be like to have Satan bound for 1000 years and not have the underlying agenda of an evil opponent deceiving the majority of people away from Yahweh and toward evil.  No fear of a government oppressing you, or killing you, or prohibiting your worship of Yahweh.  But then the opponent is let out to test the people of the world, and again many will side with him.

Reve 20:7 (NIV) When the thousand years are over, Satan will be released from his prison
8 and will go out to deceive the nations in the four corners of the earth--Gog and Magog--to gather them for battle. In number they are like the sand on the seashore.
9 They marched across the breadth of the earth and surrounded the camp of [Yahweh’s] people, the city he loves. But fire came down from heaven and devoured them.
10 And the devil, who deceived them, was thrown into the lake of burning sulfur, where the beast and the false prophet had been thrown. They will be tormented* day and night for ever and ever{*marked and remembered with dishonor for ever and ever}.

Our review has now brought us up to the point symbolized by today’s solemn assembly, the Judgment Day.  This is the day that ends all the centuries of suffering caused by the sin of Adam.  This is the day that allows the beginning of the new Heaven, the new Earth, and the New Jerusalem.  This is the day that allows the rewards to be given to the overcomers.  But the day is a realization of failure for most of mankind, and it is therefore solemn as each person that has ever lived is judged.

Reve 20:11 (NIV) Then I saw a great white throne and him who was seated on it. Earth and sky fled from his presence, and there was no place for them.
12 And I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books.
13 The sea gave up the dead that were in it, and death and Hades {the grave} gave up the dead that were in them, and each person was judged according to what he had done.
14 Then death and Hades {the grave} were thrown into the lake of fire. The lake of fire is the second death.
15 If anyone's name was not found written in the book of life, he was thrown into the lake of fire.
We remember that:  Reve 20:6 (NIV) Blessed {Praised} and holy {set-apart} are those who have part in the first resurrection. The second death has no power over them.  So we know that those of the First Resurrection, and those alive who were changed at Messiah’s coming, pass the Judgment and enter the Eternal Kingdom.

Those listed in the book of life are the righteous:
Psal 69:28 (NIV) May they be blotted out of the book of life
and not be listed with the righteous.

1.)  Those left asleep at the time of the First Resurrection were not in the body of Messiah, since the "dead in Messiah" were raised at this time.  These will be raised in the second resurrection at the White Throne Judgment, and one would expect that their names are not in the book of life.
2.)  It appears that those who worship the Beast, never had their names in the book of life:

Reve 13:8 (NIV) All inhabitants of the earth will worship the beast--all whose names have not been written in the book of life belonging to the Lamb that was slain from the creation of the world.
3.)  Some, it seems could have had their names blotted out of the book of life (if they loose their righteousness):
Reve 3:5 (NIV) He who overcomes will, like them, be dressed in white. I will never blot out his name from the book of life, but will acknowledge his name before my Father and his [messengers].
4.)  The overcomers that lived during the 1000 year period would have their names in the book of life, and would enter the Eternal Kingkom.

Now is the time for rejoicing, when you are in the kingdom; you know you have passed the Judgment.
But we are not there yet, and must not assume or take it for granted, lest we fail to overcome.
Paul said to work out your salvation with fear and trembling.
Let us at least take a peek into the kingdom:

Reve 21:1 (NIV) Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and there was no longer any sea.
2 I saw the Holy{set-apart} City, the new Jerusalem, coming down out of heaven from [Yahweh], prepared as a bride beautifully dressed for her husband.
3 And I heard a loud voice from the throne saying, "Now the dwelling of [Yahweh] is with men, and he will live with them. They will be his people, and [Yahweh] himself will be with them and be their [Mighty One].
4 He will wipe every tear from their eyes. There will be no more death or mourning or crying or pain, for the old order of things has passed away."
5 He who was seated on the throne said, "I am making everything new!" Then he said, "Write this down, for these words are trustworthy and true."
6 He said to me: "It is done. I am the Alpha and the Omega, the Beginning and the End. To him who is thirsty I will give to drink without cost from the spring of the water of life.
7 He who overcomes will inherit all this, and I will be his [Mighty One] and he will be my son.