3:5 He who overcomes will thus be clothed in white garments; and I will not erase his name from the book of life, and I will confess his name before My Father and before His angels.
He who overcomes
John, in his earlier letter in 1 John 3:1-3, says that if He, Christ, should appear that we will be like Him. That is, the purity that the washing with His blood gives to our garment makes it white. If you really want to see how He is, look at Matthew 17:1-7.
In ancient cities, the names of the citizens were recorded in a register until death. At death, their names were removed from the book of the living.
The Old Testament has the same idea. Apparently, during one of their several conversations, God told Moses about the Book of Life because Moses requests that his own name be removed from the book if God could not forgive the great sins of the people (Exodus 32:30-35).
David, says in Psalm 69:26-28, that those with iniquity should be blotted out of the book of life and not be recorded with the righteous.
Isaiah, in Isaiah 4:2-6, indicates that those left in Zion will be those "recorded for life" in Jerusalem, the Holy City.
Gradually, the book of life came to mean those people having eternal life (not just physical life). Daniel talks about the end times when those written in the book will be rescued from the time of distress (Daniel 12:1-3).
It is the greatest reason for rejoicing. Having your name in the book of life supersedes any kind of miracle performed, healing that takes place, or good deed performed (Luke 10:17-20).
The rest of Revelation refers to the book of life of the Lamb in context to those who do not follow the beast (Revelation 13:8), are not tempted by the woman riding the beast (Revelation 17:8), do not suffer the second death (Revelation 20:15), and inhabit the Holy City (Revelation 21:27).
Only a crime in ancient times could cause a persons name to be removed from the book of life (even though the person was still alive). Our place, as Christians, is more secure. Romans 8:37-39 lists all the things that might try to get our names removed from the book of life BUT won't succeed!
This is the strongest evidence of the complete and perfect work of Christ. That He will confess my name before God (Matthew 10:32-33) and His angels (Luke 12:8-10). All this while I stand there in my white, dazzling robe. WOW!!!