But you are assuming something not said in Scripture. Just because Jesus says He will not blot out the names of those who overcome, does not imply that anybody actually have their names blotted out.Therefore, that some names can be written in, or blotted out from the book of life proves people "other than the Elect" are being saved, or lost.
But the fact that you can say that names can be blotted out of the book of life seems to imply that those blotted out were alive once (spiritually alive) and then can be damned.Once a person is born again, he can't unborn. Once they are given eternal life, they have eternal life, not temporary life. Once saved always saved is clear Bible teaching. Don't confuse me with anyone who denies "the eternal security of the believer."
I found one verse in the OT that sounds similar:
Psalm 69:28 Let them be blotted out of the book of the living, And not be written with the righteous.
David is talking about all those persecuting Israel.
In Exodus when God threatened to wipe Israel out and start over with Moses, Moses replied:
Exo 32:32 Yet now, if You will forgive their sin—but if not, I pray, blot me out of Your book which You have written."
I searches for "book of life" and only found 8 verses.
Php_4:3
Rev_3:5 He who overcomes shall be clothed in white garments, and I will not blot out his name from the Book of Life; but I will confess his name before My Father and before His angels.
Rev_13:8
Rev_17:8
Rev_20:12
Rev_21:27
Rev_22:19 and if anyone takes away from the words of the book of this prophecy, God shall take away his part from the Book of Life, from the holy city, and from the things which are written in this book.
The only one that comes close to somebody having their name blotted out is the last one. And there is doesn't actually say "name blotted out," it says "take away his part from the Book of Life, from the holy city, and from the things which are written in this book."