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)
The New Jerusalem and its Heavenly Teachings #173
173. Regeneration
Anyone who does not begin to live a spiritual life-that is, who is not born anew by means of the Lord-cannot come into heaven. This is what the Lord tells us in John: "Truly, truly I say to you, unless you are born again you cannot see the kingdom of God" (John 3:3).