Jesus Christ is the one and only Head of his church. He is its author, and therefore has complete authority. Jesus, the head, has one body: his church. He does not have many separate bodies. This is an impossibility. The image of the body that we read about in the bible is always singular in nature. Many bodies with one collective head is nonsensical.
Jesus is the basis for our faith. We live for him because of what he has done and what he continues to do. Since we are all part of the family of God, we are one in him. He is the linchpin of our belief system and worldview. He holds all things together. All things are for him.
Colossians 1:15-18 sums it up well, "He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together. And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent."
Jesus has united us together in himself. We have no choice but to be united. A divided church is, in essence, an impossibility. And yet, we often live as fractured bodies, strewn about with our different little views on less than critical issues. Christ has made us one and demands that we be so. We haven't exactly been given an option in this.
As we think about our one mission together, we must keep in mind that it is Christ who unites us. We don't ultimately do it ourselves. However, this means that we must live united, putting forth the effort to make it occur on a daily basis.
The beauty in all this is that Jesus has given us all we need to live united. He has sent us the Holy Spirit to guide all we do. He has provided us with ample instruction in scripture. He has changed our hearts to look to the good of others before ourselves.
The unity of the church ought to be a given. It certainly is not an option.
Let's look to Christ as our sovereign head as we band together to get the gospel to the ends of the earth.