I love this quote from Cecil Robeck in The Mission of God: Studies in Orthodox and Evangelical Mission;
Evangelicals believe in mission because God sent his Son. and Jesus became incarnate ultimately to draw all men and women to himself (John 12:32), thereby inviting them and incorporating them into God’s own life. He did this through the proclamation of the good news of the kingdom (Matt. 4:23, 9:35; Mark 1:14) in the power of the Holy Spirit (Luke 4:18-19) and by giving his will over to the will of the Father through is incarnation, death (for our sins), and resurrection, affirmations which according to Paul, are of first importance (1Cor. 15:3-4). Those who have responded to his gracious invitation have, in turn, been instructed to follow him and engage others with the message that he brought. it is the message of a God who desires to give life. It is the message of a God who wishes to make all things new. It is the message of a God who longs to extend his kingdom throughout all of creation and who has invited us to join with him by serving as ambassadors (2 Cor. 5:18-20) on behalf of the kingdom. The Great Commission of Matthew 28:19-20, which is essentially reaffirmed in Acts 1:8, makes it clear that Jesus’ disciples, including all of us, are to ‘go and make disciples of all nations, baptising them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you.’
In the Church’s role as the primary means that God has chosen to communicate his message of Good news, the emphasis that Evangelicals have placed upon the individual once again comes into play. This emphasis on the individual may be considered its greatest strength, for in some sense it involves every Christian in the missionary task. But it is also its greatest potential weakness, in that any individual can detach himself or herself from the Church, proclaiming Christ for whatever reason, but failing to understand the crucial role that the Church plays in God’s plan. The Church, as the faithful Body of Christ who is its head, remains critically important to the tasks of evangelisation and mission because they are the will of God. These are not simply individual tasks to be undertaken as private entrepreneurial activities.