We dare not confuse divine unity with organizational unity.
Christians are one in Christ, which does not require the existence of organizational unity (John 17: 11, 22-22). The mere reality of different churches or even denominations is not necessarily demonstrative of disunity. This is because our unity is not derived from an organization but our relationship to Christ, the head of the church (Eph. 5:23).
Our unity is organic rather than organizational. Now, this unity may be expressed in various ways including an organization. However, it seems best expressed in what Jesus said, “By this all men will know that you are My disciples, if you have love for one another” (John 13:35).
My love and support should not be merely for those who are organizationally linked to me, beyond what is quite natural to such associations. As long as they preach truth, I can not only love them, and recognize our unity; I can also be supportive of their quest to present Christ. Because they do not belong to the same organization as I do, should not keep me from supporting their promotion of the gospel (Mark 9:38-41; Phil 1:14-18). Important as well is that while we do not create our unity in Christ and His love, we are called to concentrate on “being diligent to preserve the unity of the Spirit in the bond of peace” (Ephesians 4:3).
If a church’s diversity reaches such a degree that she realizes she cannot minister effectively to the whole body of believers or the whole culture, and starts a new church; such an endeavor can be done in unity and love. This is often the case.
Our unity is not at the expense of truth, but actually it is dependent upon it ( 1 Pet. 1:22; 1 John 3:18; 2 John 1, 3: 3 John 1). Unity is in love and the truth, but such does not demand agreement on every minor issue or application. Believing that it does, serves as the genesis of true disunity. True divine unity is seen when Christians love and respect one another as Christians, leaving attacks and slander to the world. Such unity does not necessitate nor find fulfillment in organizational unity.
“I am no longer in the world; and yet they themselves are in the world, and I come to You. Holy Father, keep them in Your name, the name which You have given Me, that they may be one even as We are” John 17:11.