“That they may be one”
Having prayed first for himself and then for his disciples, Jesus goes on to pray for all who will become believers as a result of the gospel message (20). It’s a prayer for the church in every place and every generation, including ourselves. In particular, he prayed “that all of them may be one” (21). He has already prayed that this will be the outcome of God’s protection of them (11), and the importance of it is further underlined by its repetition in v.22.
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In all three of these verses this unity reflects the unity between the Father and the Son (10:30; 14:11). Not only that, it’s also a participation in the Father-Son relationship. Just as Jesus is in the Father and the Father is in Jesus, so too Christians are in Jesus and he in them (14:20; 15:9). It’s that relationship which is the basis of our Christian unity (21,23), and which is the gift of God through the revelation of Jesus Christ (22).
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Such unity is the clearest possible witness to the truth of Jesus (21,23). Jesus prayed that Christians will so live in the love of God, and in the relationship of love between the Father and the Son, that “the church will be a visible revelation of the unseen Father and his love” (Bruce Milne).