The Book of Life is exactly that: A Book of Life
The scriptures talk over and over again about a “Book of Life”:
“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.” Revelation 3:5
“… and with other my fellow labourers, whose names are in the Book of Life.” Philippians 4:3
Moses and Paul were both willing to be blotted out of this book:
“Yet now, if thou wilt forgive their sin…and if not, blot me, I pray thee, out of thy book which thou hast written.” Exodus 32:32
“For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh ” Romans 9:3
“Brethren, my heart’s desire and prayer to God for Israel is, that they might be saved.” Romans 10:1
Those who have their names in this book will gain immortality. They will gain life forever at the Resurrection; the rest of humanity will be destroyed and not live forever. The Book of Life is a book that contains the names of those whom God has ordained to have immortality (2 Timothy 1:10, Romans 2:7), the rest are destroyed in body and soul as Jesus said they would be (Matthew 10:28).
Moses and Paul were willing to give up their immortality, their “living forever,” for Israel to be saved. Paul states:
“For I could wish that myself were accursed from Christ (Messiah) for my brethren…” (Romans 9:3).
Something that was accursed (Gk: Anathema) was killed and cremated in the Old Testament. (Joshua 7:15). It was never tortured forever.
Therefore, Moses and Paul made a statement of profound love for the people they loved. They were not saying they would be willing to undergo eternal torment. They were willing to be dead forever. They were willing to be killed and cremated (i.e. they would give up their immortality) if it would save Jewish people and enable them to live forever. It really is that simple.