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I don't think John would totally agree with the above statement - he'd probably want to say something like 'it doesn't matter what else you know, it's what you know and believe about Jesus that really matters'.
In John 20:31 John tells us that he has written this 'gospel' so that "you may believe that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name". John doesn't just want us to believe these things so that he can win some academic argument about 'who is Jesus?' John had seen and heard Jesus. He believed that Jesus was who he said he was. John had come to experience the life that Jesus offers - in 10:10 John calls it life to the full. And so John wants us to experience this life too.
John knows that the answers to his questions are not to be found in a concept or a philosophy. They are not to be found in obeying laws. They are to be found in a person - Jesus. Jesus who was there right at the very beginning of the story creating everything that has been created; Jesus who is God; Jesus who became a human being; Jesus who was rejected by the world.
What you believe about Jesus really does matter - it's a matter of life and death.