Albert Barnes Commentary John 20:31

"but these are written, that ye may believe that Jesus is the Christ, the Son of God; and that believing ye may have life in his name." — John 20:31 (ASV)

These are written. Those recorded in this gospel.

That you might believe, and so forth. This is a clue to the design which John had in view in writing this gospel. The whole scope or end of the book is to accomplish two objects:

1. To prove that Jesus was the Messiah; and
2. That those who looked at the proof might be convinced and have eternal life.

This design is kept in view throughout the book. The miracles, facts, arguments, instructions, and conversations of our Lord all tend to this.

This point had not been kept in view so directly by any of the other evangelists. It was reserved for the last of the apostles to collect these arguments and make out a connected demonstration that Jesus was the Messiah.

If this design of John is kept steadily in view, it will throw much light on the book, and the argument is unanswerable, framed after the strictest rules of reasoning, infinitely beyond the skill of man, and having throughout the clearest evidence of demonstration.