When people hear the claim that John wrote his Gospel with an evangelistic purpose, they’re often surprised because they’ve never heard that before. But after reading John 20:30-31, they usually admit that is the case.
However, people become very skeptical when you start reasoning based on that premise, such as deducing that John’s Gospel must tell us all that we need to be born again.
But should they? Shouldn’t understanding the purpose of a Biblical book contribute to understanding its role in the life of the church?
In his chapter “Salvation by Faith Alone” in The Fundamentals for the Twenty-First Century, George Meisinger makes several good observations about salvation, the purpose of John’s Gospel, and what can be deduced about salvation given that purpose:
John clearly states in the gospel that his purpose for writing is to show how one “may have life in [Christ’s] name” (John 20:30-31) (Meisinger, “Salvation,” p. 284).
Since the Spirit inspired John, we can presuppose that he was successful in his aim, which means his Gospel must contain all that someone would need to know to be born again:
John was “moved by the Holy Spirit” to state his purpose, thus we must conclude that he accomplished his goal, recording everything one must do to have eternal life. To suppose otherwise assumes that John either misrepresented, or failed to achieve, his purpose. A proper view of inspiration does not permit such suppositions (Meisinger, “Salvation,” p. 284).
A fallible author could leave out essential instructions. For example, an author could try writing a complete guide for caring for bees and leave out how and when to euthanize a dangerous feral bee colony (thanks to Josh Meier for the example). But could an inspired author make that kind of mistake? Could he leave out information that was essential to accomplishing his purpose for writing? Absolutely not.
What does that mean for John’s Gospel? It means John’s Gospel is normative for doing evangelism. It means you can read it and look for what is and for what isn’t required to have eternal life. If someone claims that something is necessary to be born again, and John doesn’t mention it, then the person is wrong.
On that basis, Meisinger comes to this surprising conclusion about repentance:
Nowhere does John mention or allude to repentance (metanoeō; metanoia). Since we must not suppose that John fails to teach us how to achieve eternal life, it is clear that God does not require repentance. This is not an argument from silence, but an argument about silence. John does not mention repentance precisely because it is not germane to his subject. God does not require one to repent to receive eternal life; He requires faith alone in Christ alone, period (Meisinger, “Salvation,” p. 284).
John did not fail in his evangelistic purpose. But any theory of evangelism that does not take John’s Gospel as normative probably will.