Book of life means in the bible: Spoken of by Philip. 4:3; Rev. 4:3; Rev. Luke 10:20; 12:1-4. The book of life, in one sense, is the totality of one’s thoughts or actions. It is his record. The scriptures do indicate, however, that the faithful are kept in a heavenly book. This includes their names and an account of righteous acts. DC 88;128:7.
(in Bible Dictionary)