John 15:1 "I AM the true vine, and My Father is the vinedresser."
All the things the nation of Israel was to be but failed to do so, is embodied in Jesus Christ. All the I AM statements reflect this. Isaiah 5 starts out as a love song between God and His chosen people, Israel. Israel was to be a vineyard, and despite all the love God had given tending to her, Israel had only produced bitter and sour fruit. This bitterly sour fruit is described in Isaiah 5:8-25. In the Old Testament, the nation of Israel was to be a vine or vineyard (Isaiah 5:1-7, Ezekiel 15:1-6). Therefore, God will abandon her.
So if this vineyard is abandoned, will God raise a new vineyard? Juxtaposed against Israel's failure to be a vine, Jesus states that he is the true vine. Jesus was the reality, whereas Israel was the symbol. The fruit of Jesus Christ' life was and is abundant, fresh and sweet to the taste! We as Christians some 2000 years later are the result of Jesus being the true vine!
As the purpose of a vine is to produce fruit, the focal point is on what it takes to produce fruit (John 15:2). As Christian Disciples, we are to bear fruit by remaining close to Jesus, as He is the vine and we are the branches. And why is the Christian Disciple to bear fruit? So that God the Father is glorified (John 15:8) by the Christian Disciple, and thereby proving their Discipleship. As part of the ultimate mission of Jesus to glorify God the Father (John 12:28, John 17:4), it is imperative that Jesus' disciples be fruit-bearers. This means that all Christian Disciple are to be His witnesses and therefore a commitment to mission and evangelisation is necessary. That is why the Christian prays "your kingdom come" in the Lord's Prayer (Matthew 6:10)