Summary: God would have us pray and labor mightily for unity and peace in the church.
Whatever Jesus prays for must weigh heavily on the hearts of all true believers. The Beloved Son of the Father in heaven, the second person of the Triune God, the incarnation of Word, the One who lived and died and rose again that those chosen by the Father might know the glory of God’s presence forever – the prayers of this High Priest surely arrest our attention. As we love the Lord Jesus Christ and his appearing, we will pray for and work hard for that which moves him, especially in his last prayer for us. And what is on Jesus’ heart is “the unity of the Spirit in the bond of peace.”
[Read John 17.20-21. Pray.]
[Sometimes I wonder about stories handed down to pastors. I have no way of knowing if this one is true, but the illustration is powerful and the parable is Biblical.]
So the story is told of a little child in an African tribe wandering off into the tall jungle grass and could not be found. Family and tribe members ran and stomped all day, franticly seeking to see into every hidden spot obscured by the thick grasses which rose over their heads. The end of the day brought no news. The next day a thoughtful person suggested every member of the tribe hold hands so they could comb through the grass without missing any area. Eventually they found the body of the child who had died during the cold night. Through tears the anguished mother cried out: “If only we would have held hands sooner.”
Our Trinity Hymnal includes Brian Jeffery Leech’s song, “We Are God’s People.” Verse 4 reads: “We are a temple, the Spirit’s dwelling place, formed in great weakness, a cup to hold God’s grace; we die alone, for on its own each ember loses fire: yet joined in one the flame burns on to give warmth and light, and to inspire.” “Joined in one, the flame burns on….”
Puritan pastor Thomas Manton, in order to press upon his congregation the important of unity among Christians, preached several sermons on this topic from John 17. Typical of their method of starting with an idea then exploring every related thought, Manton begins with the text we are studying, then shows seven ways in which unity in the church is the Lord’s desire. I have pulled from that sermon his main headings so that you might feel the Biblical significance of this goal.
Thomas Manton (324-329): “Observe how much Christ’s heart is set upon the unity and oneness of his members: in verse 11, he prays it for the apostles; in verse 21, the same for all believers. Let us see how much it was in the aim of Christ.  Therefore was he incarnate. He united divine and human nature in his own person, that he might unite us to God by himself, and with one another: Ephesians 1.9-10: ‘according to his purpose, which he set forth in Christ as a plan for the fullness of time, to unite all things in him’….  No one thing is so inculcated in his sermons: John 15.17: ‘These things I command you, so that you will love one another’….  In his prayers, that which he reinforced again and again is unity and love….  Christ died for this end: Ephesians 2.14-16: ‘He himself is our peace, who has made us both one and has broken down in his flesh the dividing wall of hostility by abolishing the law of commandments and ordinances, that he might create in himself one new man in place of the two, so making peace, and might reconcile us both to God in one body through the cross’….  This he aimed at in his ascension, and the pouring out of the Spirit: Ephesians 4.3: ‘eager to maintain the unity of the Spirit in the bond of peace’….  This is the goal of his gracious dispensations, he gives us grace and assurance of glory to this end: John 17.22: ‘The glory that you have given me I have given to them, that they may be one even as we are one’….  It is the purpose of his ordinances in the church. Baptism and the Lord’s Supper are to keep the saints together: 1Corinthians 12.13: ‘For in one Spirit we were all baptized into one body…and all were made to drink of one Spirit’; and 1Corinthians 10.17: ‘Because there is one bread, we who are many are one body, for we all partake of the one bread.’”
Now if Manton is correct, if unity in the church is much on the heart of the Savior of the church, then we would expect this often to be in the Apostles’ admonitions. And so it is. In addition to the verses brought out in the quote, consider these: