Toward the end of his record of the Gospel, the Apostle John makes his purpose clear: that the hearer may “believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (John 20:31). Some years later, the same apostle would pen a few letters to Christian churches. In the first letter, he gives an equally clear purpose statement: “I write these things to you who believe in the name of the Son of God, that you may know that you have eternal life.”
The similarity between the Gospel According to John and the First Epistle of John is found in the centering of each book on the person and work of Jesus Christ and a desire to connect Christ’s nature and work to the reception of eternal life in his name. The difference between the two books, while subtle, is found when considering John’s audience and how that audience relates to eternal life; in his Gospel, John writes primarily to an unregenerate audience so they may believe and have eternal life, and in his first epistle, John writes to a regenerate audience so they will know that they have eternal life.
This distinction tells us that it is possible to have eternal life yet struggle with assurance. Such was the case for John’s targeted audience for his first epistle. Many of these believers had given up much to follow Christ. During the short course of their journey, they witnessed apostasy: people whom they thought were fellow believers, with whom they fellowshipped and worshiped, fell away from the faith. All this led to many questions. Did Christ really come in the flesh? Do we really have eternal life? Is this faith worth dying for?
