If anyone's name was not found written in the book of life, he was thrown into the lake of fire. (Rev 20:15)
NOTE: Not only are names written in the book of life, names can also be blotted out of it by committing idolatry and other sins:
So Moses went back to the LORD and said, "Oh, what a great sin these people have committed! They have made themselves gods of gold. But now, please forgive their sin - but if not, then blot me out of the book you have written." The LORD replied to Moses, "Whoever has sinned against me I will blot out of my book." (Exo 32:31-33)
May they be blotted out of the book of life and not be listed with the righteous.(Psa 69:28)
Yet you have a few people in Sardis who have not soiled their clothes. They will walk with me, dressed in white, for they are worthy. He who overcomes will, like them, be dressed in white. I will never blot out his name from the book of life, but will acknowledge his name before my Father and his angels. (Rev 3:4,5)
The beast, which you saw, once was, now is not, and will come up out of the Abyss and go to his destruction. The inhabitants of the earth whose names have not been written in the book of life from the creation of the world will be astonished when they see the beast, because he once was, now is not, and yet will come. (Rev 17:8)God's foreknowledge is referred to there because God knows what man will do salvation-wise before he does it. God had the names of those who would choose to believe on Jesus written in the book of life from the creation of the world. God's foreknowledge of man's choice is also referred to here:
Peter, an apostle of Jesus Christ, To God's elect, strangers in the world, scattered throughout Pontus, Galatia, Cappadocia, Asia and Bithynia, who have been chosen according to the foreknowledge of God the Father, through the sanctifying work of the Spirit, for obedience to Jesus Christ and sprinkling by his blood: Grace and peace be yours in abundance. (1 Pet 1:1,2)
Nothing impure will ever enter it [New Jerusalem], nor will anyone who does what is shameful or deceitful, but only those whose names are written in the Lamb's book of life. (Rev. 21:27)
Dear reader, does that describe you? Remember: one's spiritual identity changes from lost to found at the point of repentance. Though one does shameful and deceitful things, if he sincerely repents of his sins and turns to the Lord Jesus to serve him (1 Thess. 1:9), that wickedness is wiped clean and forgotten. He is purified spiritually. It is one's spiritual condition at the point of death which determines where he will go (Heb. 3:14; Mt. 10:22; Rev. 2:10,11), but that is also related to having one's name in the book of life or not! Is YOUR NAME in the book of life now?
Those wolves in sheep's clothing rushed for profit into balaam's error;
Seemingly oblivious to their own awaiting unquenchable fiery terror.
Weeping and gnashing of teeth is ahead for all of the unrighteous dead.
Only those who die pure in heart go to Paradise, as the scriptures has said.
To prevent becoming one of the many to be thrown into the fiery lake,
Take this dire warning to heart and know your soul's eternity is at stake.
Be faithful to the point of death to follow the Lord Jesus and king;
Love the redeemer before your family, your own life and every other thing.
You must be able to stand alone and to even be persecuted to your death.
Don't fear those who kill the body but hold on till your last breathe.
Therefore come out from them and be separate, says the almighty Lord.
Live holy and fight the good fight of the faith and you'll never be bored.