It should be noted that God writes human works in books. For example he is recording the words we speak. Read this: But I tell you that every careless word that people speak, they shall give an accounting for it in the day of judgment. 37 For by your words you will be justified, and by your words you will be condemned.” Matthew 12:36 [NASB]. It means that our words are written in the book. God has been writing books since the beginning of creation. He will open them on the Day of Judgment.
The most important of such books is the Book of Life. It has existed since the foundation of the earth. It is in the name of Christ. Read this: ……everyone whose name has not been written from the foundation of the world in the book of life of the Lamb who has been slain. Revelation 13:8 [NASB]
For our name to be in this book, we must confess Him. Because, if our name is in this book, He says that He will confess before the Father. “Therefore everyone who confesses Me before men, I will also confess him before My Father who is in heaven. 33 But whoever denies Me before men, I will also deny him before My Father who is in heaven. Matthew 10: 32-33[NASB]. Read this also: and I will not erase his name from the book of life, I will confess his name before My Father and before His angels. Revelation 3:5 [NASB]. To confess Him means to have salvation in Him.
What if my/your name is in the Book of Life?
(1) You can rejoice that your names are written in the book of life.
Read this what Jesus told to His disciples: Nevertheless do not rejoice in this, that the spirits are subject to you, but rejoice that your names are recorded in heaven.” Luke 10:19-20 [NASB]
(2) You can enter His Kingdom to have eternal life. Read this: and nothing unclean, and no one who practices abomination and lying, shall ever come into it, but only those whose names are written in the Lamb’s book of life. Revelation 21:27 [NASB]
(3) You will be given white(glorified) garments in heaven. He who overcomes will thus be clothed in white garments; and I will not erase his name from the book of life, and I will confess his name before My Father and before His angels. Revelation 3:5
(4) You are in the list of righteous and of the first born of the Church. Read this: But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to myriads of angels, 23 to the general assembly and church of the firstborn who are enrolled in heaven, and to God, the Judge of all, and to the spirits of the righteous made perfect, Hebrews 12:23
We can notice that God can erase names from the book of life. Sinning against God can result this. That is why Moses mentioned to God to erase his name, if necessary. This was a plea made by Moses to God with regard the matter of sin of the people of Israel. Read this: But now, if You will, forgive their sin—and if not, please blot me out from Your book which You have written!” 33 The Lord said to Moses, “Whoever has sinned against Me, I will blot him out of My book. Exodus 32:32[NASB]. Also Read: …I will not erase his name from the book of life, Revelation 3:5[ NASB].
The subject of erasing names from the Book of Life can be found elsewhere in the Bible. Read this verse: May they be blotted out of the book of life And may they not be recorded with the righteous. Psalms 69:28 [NASB]
Paul, the apostle, said that the names of some of his associates were already in the Book of Life. From this we can see that God Servant had the opportunity to know in advance what names were in the Book of Life. Read this: I urge Euodia and I urge Syntyche to live in harmony in the Lord. 3 Indeed, true companion, I ask you also to help these women who have shared my struggle in the cause of the gospel, together with Clement also and the rest of my fellow workers, whose names are in the book of life. Philippians 4:2-3 [NASB]
What if your name is not in the Book of Life?
You cannot enter His kingdom and will be thrown into lake of fire(hell) for ever. Read this: And if anyone’s name was not found written in the book of life, he was thrown into the lake of fire. Revelation 20:15 [NASB] This is the second death.