That is a very good question! We will try to answer it by considering two facts:

1) The names in the Lamb’s Book of Life were written there BEFORE TIME BEGAN. Revelation 17:8 says, “And those who dwell on the earth will marvel, whose names are not written in the Book of Life from the foundation of the world” (NKJV). This means that one’s name isn’t written there because of something they do. It means that God, in His sovereign grace, wrote the names of all whom He chose to be saved BEFORE THEY WERE EVEN BORN. Ephesians 1:4 tells us, “Just as He chose us in Him before the foundation of the world.” Another verse states, “All who dwell on the earth will worship him, whose names have not been written in the Book of Life of the Lamb slain from the foundation of the world.” This teaches us that God not only wrote the names of certain people in the Lamb’s book of life before time began, but He also chose His Son to be the Lamb of God to die for sinners before the foundation of the world. In other words, the plan of salvation was designed in eternity (which involved His Son becoming the sacrificial Lamb), along with those who would be blessed with God’s wonderful salvation.

2) All who believe in Jesus Christ as the Lamb of God can be assured their names are in the Lamb’s Book of Life. Let’s read 1st Peter 1:17-21, “And if you call on the Father…conduct yourselves throughout the time of your stay here in fear; knowing that you were not redeemed with corruptible things, like silver and gold, from your aimless conduct received by tradition from your fathers, but with the precious blood of Christ, as of a lamb without blemish and without spot. He indeed was foreordained before the foundation of the world, but was manifest in these last times FOR YOU WHO THROUGH HIM BELIEVE IN GOD, who raised Him from the dead and gave Him glory, so that your faith and hope are in God.” This teaches us that it is through Christ (the spotless Lamb of God) that the believing sinner is redeemed and comes to know God as their Father. The moment we believe the good news that “Christ died for our sins…He was buried, and that He rose again the third day” (1st Corinthians 3-4), we are SAVED and have ETERNAL LIFE. Jesus made this crystal-clear in the following scriptures from John’s gospel:

“For God so loved the world that He gave His only begotten Son, that WHOEVER BELIEVES IN HIM should not perish but HAVE EVERLASTING LIFE” (3:16).

“Most assuredly I say to you, he who hears My word and BELIEVES IN HIM WHO SENT ME HAS EVERLASTING LIFE, and shall not come into judgment, but has passed from death into LIFE” (5:24)

“My sheep hear My voice, and I know them, and they follow Me. And I GIVE THEM ETERNAL LIFE, and they shall never perish” (10:27-28).

So, in answer to your question, we can’t know our names are written in the Lamb’s Book of Life UNTIL WE BELIEVE IN CHRIST AS THE LAMB OF GOD. After we believe in Jesus Christ as our Savior we are then assured, as we have just seen, that we HAVE ETERNAL LIFE. But wonder of wonders, God put our names in “the Lamb’s Book of Life” before time began and thus the logical conclusion is that we came to believe in Christ (and receive eternal life) because God chose us and wrote our names there! This is confirmed in verses such as Acts 13:48, “And as many as had been appointed to eternal life believed.”

Has my reader believed in Jesus Christ as the Lamb of God who died for you and rose again? If so, then you can “rejoice because your names are written in heaven” (see Luke 10:20). (326.1) (DO)