Book of Life
Exodus 32:33 (ESV) … But the Lord said to Moses, “Whoever has sinned against me, I will blot out of my book.”
In these verses Moses linked his appeal for forgiveness for Israel’s sin to an offer to lose his own eternal life if the people’s sin could not be forgiven. God replied that he would not give eternal life to sinners, implying both that Moses was not at fault and that he, God, was fully in charge of judging between the righteous and the wicked and would make the determination of who obtained eternal life. Thus “Whoever has sinned against me I will blot out of my book” (v. 33) represents a statement of divine practice, a standard of justice that God maintains—as well as a strict warning that eternal life is not automatic and that a person who tries to enter it without his sins being forgiven could not succeed. Verse 33 is, then, one of the Bible’s stronger statements about the absolute necessity for the forgiveness of sins, and therefore, for a savior. It can be regarded as implicitly messianic even if not overtly so.
Moses’ offer to be blotted out of the Book of Life (along with, not instead of, the Israelites) was selfless and noble, showing his deep identification with the people. He was willing to go beyond even what he had said earlier in vv. 11–13 and give up on his own future lest the people he had led would have no future by reason of their “great sin.”
 Stuart, D. K. (2006). Exodus (Vol. 2, pp. 684–688). Nashville: Broadman & Holman Publishers.