When does eternal life begin?

This is actually very simple.  Again, in John 3:16, it says that if we believe then we will not perish, but have everlasting life.  Every time we see this throughout the Book of John it implies that eternal life begins the moment you believe.  In Romans 6:4 it states that we who believe in Him “have been buried with Him through baptism into death in order that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life.”  Also, Romans 6:11 states, “Even so consider yourselves to be dead to sin, but alive to God in Christ Jesus”.  2 Corinthians 5:17 states, “Therefore if any man is in Christ, he is a new creature, the old things passed away; behold new things have come.”   Galatians 2:20 states, “I have been crucified with Christ; and it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself up for me.”  And Ephesians 2:10 says, “For we are His workmanship, created in Christ for good works, which God prepared beforehand, that we should walk in them.”

Looking back at each of these passages, it is obvious that we could not have a change, receive a new creation, etc. without receiving eternal life.  Therefore, eternal life begins at the moment we believe in Jesus Christ.