Does the Lord's statement (above) imply that it is possible to be blotted out of the Lamb's Book of Life, thus loosing one's salvation? There are many passages which seem to suggest that names can be blotted out of God’s book.
For example: Ex 32:33; Psa 69:25-28; Deu 9:14; 25:19; 29:20; Rev 3:5

However, if the book in question is "the Lamb’s Book of Life" in which are written those who are joined to Him through the new birth, by faith in His one sufficient sacrifice (the blood of the Lamb)... the possibility of being "blotted out" would stand in contradiction to the impossibility of being plucked from the hand of the Good Shepherd who gave His life for the sheep. Joh 10:27-30; cp. Joh 6:37; 17:11; Heb 13:20,21; Jude 24

Many suggestions have been offered to reconcile this apparent conflict between the various passages. However, the confusion disappears when we realize that these passages are not all speaking about the same book.

In the prophetic foreview of the Great White Throne judgment (Rev 20:11-15), “the books were opened: and another book was opened, which is the book of life...” The book of life is evidently identical to the Lamb’s book of life (Rev 13:8). But what are the other books? We are not given their titles, nor are we told how many books are opened. But some are mentioned elsewhere in Scripture in reference to judgment.

• The Bible is the standard of judgment (Joh 5:39,45-47; 12:48; Luk 16:31)
• The law written in the hearts (the conscience) is the standard of judgment for those “having not the law” (Rom 2:12-16)
• The record of each individual’s works (Rev 20:13) demonstrate that all fall short of the standard.
• The registry of "the dead" who occupy hades ensure that all are accounted for (Rev 20:12-14). Can any name be listed here that was not previously listed among “the living”?

The following passages have been grouped according to the book or books, to which they seem to allude...

The Book of life - the rolls of those who have received natural life...

• Psa 69:25-28 - "blotted out of the book of the living" (referring to removal from natural life in judgment), "not written among the righteous" (referring to not being included among the redeemed who have eternal spiritual life. This exclusion is also a judgment for sin. But having never been written in, they are not blotted out of this volume.)
• Deu 9:14; 25:19; 29:20 - To be "blotted out from under heaven" apparently refers to removal from earthly life, as a judgment for sin. Note that the Amalekites would not have been included in the book of spiritual life, due to their perverse religious heritage, and therefore would not be removed from the rolls of the redeemed.
• Psa 139:16 - The instructions written in our DNA define the human being that will emerge from the moment of conception. This is true of all men, regardless of their spiritual heritage. The Lord’s intimate knowledge of every person, and especially of the redeemed is described elsewhere in the Psalm. However, the "book", referenced in this verse, relates specifically to human development in the womb.

The Books of Remembrance - These are an individual's works (good and bad), heart attitudes and all other factors which will be taken into consideration at the final judgment. (These passages provide only a sampling of what the Lord knows about each person.)...

• Neh 13:14 - deeds
• Psa 56:8 - tears
• Isa 65:6 - rebellion requiring recompense

The Book of Life (the Lamb’s Book of Life), the rolls of the redeemed who have eternal spiritual life.

• Ex 32:32,33 - It was not possible to blot Moses’ name from God’s Book, because he had eternal life. If that is the case, what does God have in mind, when he says: "The one who sins, him will I blot out of my book."? Perhaps God was thinking of another book... the roll of the nation of Israel. Just a few verses earlier, God had threatened to discard the entire nation of Israel and instead make of Moses a nation (v.10). Elsewhere, He mentions the possibility that an individual sinner could be removed from the congregation of Israel (eg., Ex 12:19).
• Dan 12:1
• Php 4:3
• Rev 3:5 - The point here is that a true believer ("he that overcometh") is secure in the Book of Life, because the Lamb confesses his name (identifies him as His own) before the Father. (Note that He does not say that any name will ever be blotted out.)
• Rev 13:8 - This verse can also be translated: "whose names are not written from the foundation of the world in the book of the Lamb slain." Compare that reading with Eph 1:4. Who are "the chosen in Him before the foundation of the world"? They are identified (in Eph 1:12,13) as those who have trusted in Christ and who were, therefore, sealed by the Holy Spirit of promise. Their names are eternally secure in this book, from eternity past, through the foreknowledge of God. The names "not written" in this book, from eternity past, cannot be blotted out, because they had never been written in.
• Also see: Rev 20:15; Rev 21:6.27; Rev 22:1,2,14-17,19 - Only those, who are partakers of the water of life and of the tree of life (ie., those who have placed their faith in Christ), are included in the Book of Life. Those who disregard or edit God's Word to suit themselves will have no part in the promises which belong to God's children.

Someone might ask: What about a child who has not reached the age of accountability? Is his or her name included in the Book of Life, on the basis of a parent’s faith? If so, can it blotted out if that child turns away from the faith in later years? (Understanding that an infant is sanctified through identification with a believing parent, many christian parents who have lost a child in infancy have been comforted by the thought that someday they will be reunited with their child in Heaven. See 1Cor 7:14; 2Sam 12:22,23)

The short answer is "the Lord knoweth them that are His" (2Tim 2:19). He knew from eternity past that child (of believing parents) who would die in infancy, and included him/her with them. Likewise, He knew from eternity past that child who would reject a godly heritage, and the salvation freely offered in Christ, and sorrowfully, never included his/her name in the Lamb’s Book of Life.

In summary, the Lamb's Book of Life is the eternally unchangeable registry of those individuals who are identified with Jesus Christ through faith in His person and work, by which He has secured for them eternal life and security (Joh 10:28). The names of the redeemed can never be blotted out. The names of those who never receive the salvation, which Christ freely offers, have never been included.