Revelation 21:8; Their Part in the Lake Which Burneth with Fire and Brimstone
Revelation 21:8 (KJV) But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
“Their part” refers to the inheritance of those who have excluded themselves from the eternal city, an inheritance that contrasts boldly with that of the blessed (v3-7).
Revelation 21:3-7 (KJV) And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God. And God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away. And he that sat upon the throne said, Behold, I make all things new. And he said unto me, Write: for these words are true and faithful. And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely. He that overcometh shall inherit all things; and I will be his God, and he shall be my son.
These whose names are missing from the Book of Life (Revelation 20:15) will join Satan, the beast, and the false prophet in the lake of fire and brimstone (Revelation 19:20; 20:10, 14-15).
Revelation 20:15 (KJV) And whosoever was not found written in the book of life was cast into the lake of fire.
Revelation 19:20 (KJV) And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
Revelation 20:10 (KJV) And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
Revelation 20:14-15 (KJV) And death and hell were cast into the lake of fire. This is the second death. And whosoever was not found written in the book of life was cast into the lake of fire.
This statement says nothing about their non participation in the New Jerusalem, but the positive statement about being in the lake of fire implies such a penalty and more (Alford). These are those who had no part in the first resurrection (20:6).
Revelation 20:6 (KJV) Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
[Robert L, Thomas, Revelation 8-22 – An Exegetical Commentary, Moody, 1995, 451-452]