"Who was Jesus talking about? Only unbelievers? Is that your theory?"
That is who John is talking about in Rev. 20. Believers have already been judged at Calvary and on physical death their works are judged. That's why Paul can say a crown of righteousness awaits him or to be absent from the body is to be present with the Lord. There is no holding one's breath to see if he gets a prize sometime in the future for the believer; he is in the presence where all is manifest before the One with whom we have to do.
When the Great White Throne judgment takes place the marriage supper has already taken place and the believers are already clothed. They have nothing to fear from Him who sits on the throne. They are not disembodied spirits for they are clothed. This judgment is for the unbelievers of all ages and it is a judgment for works that determines the severity of their eternal punishment (Matt. 11:21-22, "Woe unto thee, Chorazin! woe unto thee, Bethsaida! for if the mighty works, which were done in you, had been done in Tyre and Sidon, they would have repented long ago in sackcloth and ashes. But I say unto you, It shall be more tolerable for Tyre and Sidon at the day of judgment, than for you").
"15 And anyone not found written in the Book of Life was cast into the lake of fire." Is just a statement where the eternal punishment is to take place. The unbelieving dead already know their names are not written in the Book of Life for where they are the presence of God is not.
Interesting theory. I've seen it before in dispensationalism. Another "rightly dividing" disconnect. I've have to see the proof from specific verses to take it seriously.
They are not disembodied spirits for they are clothed.
What do they put their clothes on if their bodies are still in the grave? You've not spiritualizing the condition of the saints, are you?
You haven't mentioned Matthew 25:31ff; the judgment of the sheep and goats. One judgment or two. Believers and unbelievers, or no? These sheep are not believing sheep but some other set of sheep. "I am the good shepherd. The good shepherd gives His life for the sheep. ... and I know My sheep, and am known by My own."
Simple reading of the text, or dispensationally/unnecessarily complex?