Shortly before He went to the cross, Jesus prayed for unity among His followers: “Holy Father, protect them by the power of your name, the name you gave me, so that they may be one as we are one” (John 17:11).
Later in the same prayer, Jesus asked “that all of them may be one, Father, just as you are in me and I am in you. May they also be in us. . . . I have given them the glory that you gave me, that they may be one as we are one—I in them and you in me—so that they may be brought to complete unity” (John 17:21–23). Obviously, Christian unity is important to our Lord.
Jesus not only prayed for unity, but He gave the reasons that Christian unity is important: He asked that all believers may be in the Father and the Son, “so that the world may believe that you have sent me” (John 17:21). And then Jesus prayed for “complete unity” so that “the world will know that you sent me and have loved them even as you have loved me” (verse 23). When Christians are united in Christ, the world sees two things clearly: Jesus was sent by the Father, and Jesus loves His church.
In Romans 15:5–6, we see another, more general reason that Christian unity is important: “May the God of endurance and encouragement grant you to live in such harmony with one another, in accord with Christ Jesus, that together you may with one voice glorify the God and Father of our Lord Jesus Christ” (ESV). The bottom line is God’s glory. God’s people should be speaking with one voice in glorifying God.
Christian unity comes with Christian maturity, and it is always something that we strive to attain. Paul instructs us to “make every effort to keep the unity of the Spirit through the bond of peace” (Ephesians 4:3). Helping us toward that unity are the gifts of the Spirit. God has given each Christian different gifts, and their exercise in the edification of the church leads to more and more unity. One purpose of the gifts is that “we all reach unity in the faith and in the knowledge of the Son of God and become mature, attaining to the whole measure of the fullness of Christ” (Ephesians 1:13).
To promote Christian unity, God presents the church in 1 Corinthians 12:12–27 as a living body. The body has many members, each with specialized work to do, but all the parts are united in the Head of the Body, which is Christ (see Ephesians 4:15).
Christians naturally form local communities in which no one needs to rejoice or suffer alone (Romans 12:15; 1 Corinthians 12:26). Christians from many different backgrounds working in unity display the power of the gospel and the universality of its saving message (Galatians 3:26–28). Christians bring honor to God’s name by pursuing unity in the power of the Holy Spirit who brings us together as one through faith in Christ.
Christian unity is a virtue, but there are some things that can and should limit unity. We don’t pursue unity simply for the sake of unity; it is Christ and His truth that unite us. Scripturally, we are to separate from professed brothers and sisters in Christ who live in persistent, unrepentant sin (Matthew 18:15–17; 1 Corinthians 5:1–2) and from those who teach false doctrine (Revelation 2:14–15). “Watch out for those who cause divisions and put obstacles in your way that are contrary to the teaching you have learned. Keep away from them” (Romans 16:17).
As Ephesians 4:13 intimates, we won’t reach full Christian unity until we attain “to the whole measure of the fullness of Christ.” So we probably won’t fully realize Christian unity in this world. But we strive for it. The unity that faith in Christ brings extends God’s love on earth and demonstrates the truth of who Jesus is. Unity in the church also foreshadows the worship in heaven, where a great multitude “from every nation, tribe, people and language” stands before God and cries out with a loud voice, “Salvation belongs to our God, who sits on the throne, and to the Lamb” (Revelation 7:9–10).