The book of life

God has a record of those who belong to him:
Phil (NIV) 4:3 Yes, and I ask you, loyal yokefellow, help these women who have contended at my side in the cause of the gospel, along with Clement and the rest of my fellow workers, whose names are in the book of life.
Can your name be blotted out of the Book of Life?
Ex 32:33 Whoever has sinned against me I will blot out of my book.