In order to be a church, the people must assemble in the name of Christ. In so doing, they attest that he is the determining ground of their lives; in him they have found freedom, orientation, and power. They come together first of all to call upon him as Savior and to bear witness to him before each other and before the entire world. They hear the proclamation "in his name" (Acts 5.28), call upon his name in faith (see Rom. 10.13), are baptized in his name (see Acts 2.38), and in this way are "washed," "sanctified," and "justified" through this name (1 Cor. 6.11). He is the source of their lives.
Second, people gather together in Christ's name in order to profess faith in him as their Lord and as the Lord of the entire cosmos. He determines the fundamental conditions of their individual and communal lives (see 1 Cor. 1.10; 5.4); they gather together "under his authority and with the intention of acting in obedience to him." It is he who gives their lives binding direction.
Third, by assembling in Christ's name, Christians acknowledge him as the power in which they live. The "power" and the "name" are intimately connected. Jesus Christ is Immanuel, the God who is with them, and in the power of his Spirit they are able to do those works that are commensurate with the new creation and that allow the new creation to shine in the midst of the old.
-- from After Our Likeness: The Church as the Image of the Trinity by Miroslav Volf