Emil Brunner once made this incisive statement: "The church exists for mission as a fire exists in burning."

The doctrine of the church is intimately connected with the notion that Christianity is a missionary religion. The two cannot be separated. Gary Badcock makes some significant observations regarding the mission of the church in his book, The House Where God Lives (some of which I noted earlier), and in the following paragraph, calls us to remember that mission is absolutely central to the church's identity, reflective of the insights of missiologists such as Lesslie Newbigin and David Bosch. This will be the last portion I take from his book for now, and so I leave the final word to him:

Much of this biblical insight [on the church's mission] is also present in the doctrine of the Trinity, according to which, through the sending of the Son into the world, and through the gift of the Spirit, the Father shows himself to be open to the creation, inviting it into his life. The work of the Son and the Spirit, the 'two hands of the Father' (Irenaeus), reveals that God takes a 'hands-on' approach to the world, an approach that is directed to our becoming 'participants of the divine nature' (2 Pet. 1:4). This theme has had an impact on recent missiological thought: it appears in the concept of the missio Dei movement, which was developed in the context of the ecumenical work of the International Missionary Council in the mid-twentieth century...According to one of the documents issued in connection with its 1952 conference in Willingen, Germany:

The mission is not only obedience to a word of the Lord, it is not only the commitment to the gathering of the congregation; it is participation in the sending of the Son, in the missio Dei, with the inclusive aim of establishing the lordship of Christ over the whole redeemed creation. The missionary movement of which we are a part has its source in the Triune God Himself.

According to this...view, mission is not simply something the church does, as it were, among its several other tasks and duties. Nor would it be strictly accurate as a matter of theological principle to say that the task of mission belongs to the church. Rather, since the mission is fundamentally God's, and since the church merely participates in it, the church belongs to the missio Dei rather than the missio to the church. Therefore, mission precedes the church and is utterly fundamental: it is effectively the womb from which the church is called into being. Or, to put it another way, it is only by virtue of the church's participation in the divine mission that it actually comes into existence. In this strictly theological sense, then, mission is nothing less than the source and content of all ecclesiology.