Most people focus on the part of this that promises us we won't perish. It's certainly a wonderful promise, but, it's not the focus of the verse. The primary purpose of Jesus' coming to this earth was not forgiveness of sins, but to give us eternal life.
Sin separated us from God so Jesus dealt with sin. His payment for sin was just a step toward His ultiimate purpose of reconciling man to God. If someone believes that Jesus died for their sins but doesn't go on to enter into the close fellowship with God that Jesus made available, then they are missing eternal life.
Eternal life is not a length of life, but rather a quality of life. Eternal life is knowing the Father and Jesus (John 17:3). Many people have been done a disservice in being told that Jesus came to forgive us of our sins "period'. If it had been all that He did, it would have been wonderful--and much more than we deserved--but much less than what He actually accomplished.
We must take full advantage of our salvation and go beyond the basic forgiveness of our sins into really knowing the Almighty God.
