Revelation 12:12: Therefore rejoice, ye heavens, and ye that dwell in them.

The war in heaven was fought on the premortal spirit world called Kolob.¹ The war ended when Satan and his rebellious angels were cast down from heaven (Kolob) to this physical earth as unembodied spirits in Revelation 12:8-10.² The premortal spirits that were on Kolob at that time and who kept their first estate had great cause to rejoice because: (1) Satan and his angels were cast down,³ (2) salvation had come to the premortal spirits that kept their first estate on Kolob,⁴ and (3) this physical earth had been created as the place for their future mortal existence.⁵

The words cast out or cast down appear four times in Revelation 12:9-10 to describe how Satan and his angels were expelled from Kolob when the war in heaven ended.⁶ This was the cause of rejoicing in Revelation 12:12. By way of comparison and contrast, Revelation 12:4 states that the Dragon's tail drew the third part of the stars of heaven, and did cast them to the earth.⁷ However, there is no mention of rejoicing in Revelation 12:4. Doctrine and Covenants Section 76:25-27 further states that the heavens actually wept when Lucifer fell.⁸ The words in 12:4 and 12:9 are similar, but the emotions are exactly opposite. This occurs because verse 4 describes Lucifer's spiritual fall at the time of the grand council, when there was reason to weep,⁹ whereas in Revelation 12:12 there was reason to rejoice by reason of Satan's defeat.

Revelation 12:12 states that the heavens (plural)¹⁰ rejoiced because the war in heaven ended, including them that dwell in them.¹¹ There are actually many heavens,¹² but three groups or types of heaven must have rejoiced with their inhabitants in verse 12, as follows:

1. The most obvious heaven is Kolob itself.¹³ Kolob is the spirit world within this earth.¹⁴ It was joined to this physical earth at the time of the physical creation when the war in heaven came to an end.¹⁵ After Satan was expelled with his angels, the premortal spirits that remained on Kolob were those that kept their first estate.¹⁶ They had great cause to rejoice because Satan and his angels were cast down from their premortal home in their first estate and this physical earth had been created to become the place of their second mortal estate.¹⁷
2. The second group of heavens includes countless other worlds and their inhabitants in this generation that Christ created before this earth.¹⁸ By the time the war in heaven ended on Kolob, these other worlds had already passed away.¹⁹ Their righteous inhabitants were disembodied spirits and/or translated people²⁰ who were waiting for their resurrection at the time of Christ's infinite atonement and resurrection on this earth.²¹ They had great reason to rejoice in their heaven when this earth was created because Christ's atonement and resurrection on this last earth of this generation would be for their benefit.²²
3. The final group of heavens includes countless resurrected worlds²³ and their inhabitants of the celestial kingdom from past generations,²⁴ including the celestial residence of God the Father.²⁵ Each resurrected and glorified celestial heaven is a great Urim and Thummim.²⁶ Therefore, the glorified inhabitants in these celestial kingdoms from past generations of Gods had the ability to see and rejoice in Kolob's progress and premortal salvation in this generation.²⁷