Mt 16:16,19, Jn 1:12, 1 Jn 5:1, Rev 13:8, Rev 17:8, Rev 20:12,15, Rev 21:27, Ps 69:28, Lk 10:20, Phil 4:3, Rom 8:38-39

The Old Testament tells us that those who have been saved have their names written in the book of life. (Psalm 69:28)

Psalm 69:28 Let them be blotted out of the book of the living, and not be written with the righteous.

Those who believe that Jesus is the Christ, their names are written in the book of life in heaven. (Matthew 16:16, 19, John 1:12, 1 John 5:1, Revelation 3:5, Luke 10:20, Philippians 4:3)

Matthew 16:16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God. 19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.

John 1:12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:

1 John 5:1 Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.

Revelation 3:5 He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels.

Luke 10:20 Notwithstanding in this rejoice not, that the spirits are subject unto you; but rather rejoice, because your names are written in heaven.

Philippians 4:3 And I intreat thee also, true yokefellow, help those women which laboured with me in the gospel, with Clement also, and with other my fellowlabourers, whose names are in the book of life.

Those who do not believe that Jesus is the Christ, their names are not written in the book of life in heaven. And they are thrown into the lake of fire. (Rev 13:8, Rev 17:8, Rev 20:12,15, Rev 21:27)

Rev 13:8 And all that dwell upon the earth shall worship him, whose names are not written in the book of life of the Lamb slain from the foundation of the world.

Rev 17:8 The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.

Rev 20:12 And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works. 15 And whosoever was not found written in the book of life was cast into the lake of fire.

Rev 21:27 And there shall in no wise enter into it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie: but they which are written in the Lamb's book of life.