When I first began to understand John 17 I realized that Jesus’ greatest desire for his disciples was that they would live this oneness together. He wanted them to be united as a powerful witness to the reality of the relationship between the Father and the Son. His prayer is that our becoming one will be the catalyst for people to come to know God’s love. I had never clearly seen this before. I had engaged in evangelism since I was twelve years old, but I had never known that unity between believers had anything to do with evangelism and mission. But this is precisely what is said in the prayer: “As you, Father, are in me and I am in you, may they also be in us, so that the world may believe that you have sent me. . . . so that the world may know that you have sent me and have loved them even as you have loved me . . .” (John 17:21, 23, NRSV).
Christian unity in growing relationships is clearly God’s design for how the world will see that God loves them. When the world sees true love between Christians then people will believe that the Father “loves” them. Let me put this quite simply.
God loves the world and sent his Son into the world as the fullest (and final) expression of his eternal love. Jesus did not come into the world to condemn the world but rather that the world might be saved through him (John 3:16-17). What does Christian unity have to do with the love of Christ? Everything! Christian unity provides the real life context in which people can “see” God’s love in action.
It has been said that what we are speaks so loudly that what we say means very little. I think this is pretty close to what Jesus says in John 17. If our relationships are broken, hostile, and filled with bitterness, then the world will rightly look at us and reject our message. It is really pretty simple. If our love is too small the mission he gave us will not bear abundant fruit.