Resurrection, the first
'The first resurrection,' mentioned in Revelation 20:5, 6, does not mean a first resurrection, but the essence and primary part of resurrection, which is salvation and eternal life. There is only one resurrection to life. A second does not happen, and is not mentioned anywhere in the Bible.
(References: Apocalypse Explained 6; Apocalypse Revealed 851; Revelation 20:5-6)
Revelation 20:5-6
5
The rest of the dead didn't live until the thousand years were finished. This is the first resurrection.
6
Blessed and holy is he who has part in the first resurrection. Over these, the second death has no power, but they will be priests of God and of Christ, and will reign with him one thousand years.
