And he is the head of the body, the church.
Colossians 1:18a ESV
Who is Jesus? In the hymn of Colossians 1:15-20, that question is answered in a number of ways. Here, he is described as the head of the body, the church.
The word translated here as church is ekklēsia, an assembly of people, usually called together for a purpose. You can find this word used in Acts 19:39 to refer to the administrative assembly of a city and in Acts 19:41 to refer to a mob of people who had assembled in protest.
Paul and others co-opted this word to refer to the assembly of believers called out of the world. The word is used in the sense of a local church (1 Cor. 1:2), often meeting in homes (Rom. 16:5). And it is also, as here, used in the sense of a universal assembly of all believers.
Jesus is the Head
Jesus is the administrative head of that assembly. He directs the assembly, assigns tasks, allocates resources, and holds the assembly accountable for their actions.
Within local assemblies, Christ has work for each member. Some serve in leadership roles, and others in various other ministry roles. But each one is responsible to Jesus as the head.
However, there is another way that Jesus is understood as the head. One of Paul’s common descriptions of the church is an organic body (1 Cor. 12:12-31). A body is composed of many parts, all connected together, each serving a specific function. And one of those parts is the head, which controls the rest of the body.
Jesus is that head, providing direction to his church. As in the human body, the church is composed of many members, each with a function to carry out. When each of us is properly connected to the head and functioning correctly, the body will be healthy and productive (Eph. 4:16). But when not, the body will be sickly. Or even dead.