Salvation is a work of God's grace from start to finish. The gospel of God's grace-the good news that Jesus died for our sins and rose again-not only saves us from the penalty of sin, but removes the power of sin and trains us to be transformed into the likeness of Christ as we wait for the fullness of our transformation at His second coming when we will be finally freed from the presence of sin.
Each and every one of us has sinned and fallen short of the glory of God. There is none good, not even one. Even if we won't admit that there is a God to whom we are accountable, we can't escape His law that is written on our hearts and the conscience He placed within us that burdens us with the weight of the real guilt we carry. We are helpless to do anything about it, but the wonderful news of the gospel is that God has done what we could not. This is what Christians celebrate and commemorate on Good Friday.
That You May Believe John's epilogue balances out the prologue to his Gospel and brings it full circle, pointing us back to 1:1 where we were introduced to the eternal Word who took on flesh and dwelt among us. Jesus is glorious, and John wrote about Him to show who He is. When we believe in Him as the Christ, the Son of God, we have life in His name.