Summary: These verses summarize the Book's strategy, subject, & purpose. The strategy was to use selected works or "signs" of His subject, Jesus, which illustrate Jesus' character, demonstrate His power, & relate Him as the answer to man's great needs.
JOHN 20: 30-31
ENCOUNTERING GOD'S PURPOSE
For many scholars these last two verses of chapter 20 constitute the conclusion of John's Gospel with chapter 21 being John's personal appendix. These verses summarize the Book's strategy, subject, and purpose. The strategy was to use selected works or "signs" of His subject, Jesus, which illustrate Jesus' character, demonstrate His power, and relate Him as the answer to man's great needs.
John's purpose was a doctrinal one, and he tells us that in carrying out God's purpose he omitted many things that he could have put in had he chosen. For John's teaching aim was subordinate to advance a still further purpose. His objective was not only to present the truth that Jesus was the Christ, the One and Only Son of God, but to present it in such a way as to induce his readers to believe in Jesus Christ (CIT). The reason He wanted them to believe in Jesus was so that they might have eternal life.
This purpose of John may be applied much more widely than to his Gospel. We may use it to point our thoughts to the strange silences and subjects of the whole of Revelation of God because of this overarching purpose which God had in view. For Scripture was written according to the purpose of God, its ultimate Author, to bring about the salvation and sanctification of man.
I. THE INCOMPLETENESS OF SCRIPTURE, 30.
II. THE SELECTIVE PURPOSE OF SCRIPTURE, 31a.
III. THE ULTIMATE PURPOSE OF THE SCRIPTURES, 31b.
FIRST, THE INCOMPLETENESS OF SCRIPTURE, 30.
In verse 30 John makes it clear that he took selections of Jesus' life by intent or for a purpose. Therefore many other signs Jesus also performed in the presence of the disciples, which are not written in this book;
John acknowledges that Jesus furnished "many other signs" (semeia) to His disciples. Only seven of these were narrated, not including the final sign, Jesus' resurrection from the dead. Each sign involved a person and showed how the power of Jesus can be applied to human life. The disciples witnessed Jesus performing them as did the others present, be they friend or foe. The magnitude, type of individuals, situations, and effect of these recorded signs varied widely.
So the selection of signs offered here in John's Gospel is a small collection of those Jesus performed. This means that John was witness to a wealth of material about Jesus and that he, as a writer, had to make a careful selection to suit the burden God had placed upon him.
There is nothing in John's Gospel about Christ's birth, nothing in it about His baptism, nor about His selection of His Apostles. There is scarcely anything about the facts of Jesus' outward life at all. There is scarcely a word about the whole of His ministry in Galilee. There is not one of His parables, there are only seven of His miracles before the Resurrection, and two of these also occur in the other Evangelists. There is scarcely any of Jesus' moral teaching and no word about the Lord's supper.
I could go on delineating the many gaps in this Gospel. Nearly half of it is taken up with the occurrences of the last week of Jesus' life, and the incidents of and after His Resurrection. The largest portion of the remainder of the book consists of several conversations which are based upon miracles that He performed principally for the sake of the conversations.