Shared ground
These verses close the “great white throne” scene by showing a final, decisive outcome. The vision treats Death and Hades as realities that can be removed from the story: they are “thrown into the lake of fire.” Then the text explains its own image: “the lake of fire” is “the second death.”
The passage also applies that same outcome to people. The stated criterion is whether someone is “found written in the book of life.” If not, that person is also “cast into the lake of fire.” The movement is from the end of death’s domain (Death and Hades) to the final sentence concerning individuals.
Where interpretation differs
1) What “Death and Hades” are in the vision. Some read them mainly as places (the realm of the dead) being emptied and then abolished. Others read them more as powers or personified forces that keep humans under death’s rule, now finally ended.
2) How to understand “the lake of fire / second death.” Some take the image as describing a real, ongoing state of punishment beyond ordinary death. Others think the point is ultimate destruction: “second death” means a final death with no return, and the “lake” is symbolic language for that end.
3) How the “book of life” relates to the other “books.” In the wider scene (20:12), multiple books are opened. Some infer that the “book of life” is the decisive register, while the other books function as the public record of deeds. Others infer a tighter link: the books together show both the reality of a person’s life and whether their name belongs in the book of life.
Why the disagreement exists
Revelation communicates through visions and images, and this passage itself gives only one direct explanation (“This is the second death”). It does not spell out whether the “lake of fire” is a literal location, a symbolic picture of final ruin, or how long the condition lasts. It also does not explicitly describe how names are written in the book of life, only what follows if a name is not found there.
What this passage clearly contributes
Explicitly, the text claims: (1) Death and Hades are thrown into the lake of fire; (2) the lake of fire is identified as “the second death”; (3) anyone not found written in the book of life is thrown into that lake. The passage’s clear contribution is that the final judgment ends the old order—death and the realm of the dead do not continue—and it portrays a definitive, irreversible endpoint for those excluded from the book of life (Revelation 20:14–20:15).