John 20:30-31 - Why This Book Was Written
30 Jesus performed many other [miraculous] signs in front of His disciples which are not recorded in this book [i.e., in the Gospel of John]. 31 But these [signs] are written down so that you will believe that Jesus is the Christ, the Son of God, and that when you believe [this], you will have [never ending] life in His name [i.e., through His person and work].