What does that mean?Everyone is into this world born once, but only a few are born again (i.e. twice), Jn 3:3-5; 1 Pt 1:3,23. Those who are born only once, will die once through sin (Rom 6:23) and the second time in hell. Hence the “born once, die twice” description.
“Blessed and holy is the one who has a 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 for a thousand years.” Rev 20:6.
But those who are born twice, they die once because they are sinners, but their second birth as a Christians ensures they will not suffer in hell, the second death. They, like everyone, died spiritually because of their sin (Rom 6:23) but these have eternal life and do not suffer hell because they took part in the first resurrection at baptism, Romans 6:3-5; Colossians 2:12,13.
The Kingdom of Christ, which was “at hand” when John the Baptist preached, had a beginning and an end. The 1000 symbolic years makes the period limited. It began at the Ascension of Christ and it ends when Jesus returns and hands over the kingdom to the Father, All the verses are there. This refutes the premillenialist doctrine.
“Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire.” Rev 20:14; cf Rev 21:8