In the fall of 1933, the year of Adolf Hitler’s ascent to power as Chancellor of Germany, Dietrich Bonhoeffer left Berlin to become the pastor of two German speaking congregations outside the city of London. Bonhoeffer’s sermons in London are an attempt to work out the pastoral import of his theological convictions in the form of preaching as “homiletical theology.” His primary concern was the renewal of the congregation and its ministry as a local appropriation of the gospel. Bonhoeffer’s time in London could be seen as preaching in exile, a time of voluntary silence that was necessary for discerning how to speak of God and the church in a future that was still unknown. The London sermons warrant more attention than they have received, since what is remembered most from this period in Bonhoeffer’s life are other important commitments that occupied him on a much larger, public stage: ecumenical work, the viability of the Confessing Church in Germany, the continuing struggle with the Reich Church leadership, and resisting increasing pressure from a controlling Nazi state. Although seemingly less important in relation to Bonhoeffer’s visibility in either German or ecumenical church matters, his preaching ministry with two small congregations of expatriates illuminates his importance as a preaching theologian engaged in a struggle for truthful proclamation of the gospel.
Bonhoeffer’s first sermon in London is indicative of the manner in which he approached his responsibilities as a preacher. It also reveals his expectations for the congregations as his partners in the ministry of the Word. The sermon text he chose was 2 Corinthians 5:20, “So we are ambassadors for Christ, since God is making his appeal through us; we entreat you on behalf of Christ, be reconciled to God.”
Bonhoeffer begins with a comment on the change of pastors, and that such transitions always affect both a pastor and the people. He spoke briefly of the work of pastoral ministry and the close relationships that bond a pastor and people. There is a sense of loss and sorrow when a beloved pastor leaves, bringing uncertainty about the future. 
Bonhoeffer had other important matters on his mind. He thus shifts the focus by inviting the congregation to see its life in light of the work of God present in Christ. “Between you and your pastor should only be Christ. The important matter between you and your pastor, wherever we meet, whether in serious or joyful moments, is always Christ.” Indeed, the pastor is devoted primarily to Christ and serves the people by his or her devotion to Christ. The congregation also shares in this responsibility by allowing the Lord of the church to lead them, rather than clinging to the pastor. Attention should be directed to the preaching rather than the preacher, aided by these important questions: “Is this truly the gospel of our God?” “Is the pastor giving us stones or bread?”
Bonhoeffer’s introductory sermon aimed to clear a space for the word to be spoken, heard and believed. There was also a prophetic aim to call the church to return to God, to recognize God’s truth is to be trusted, and to choose the “holy restlessness of God.” This leads to a remarkable description of preaching as something unique in all the world and completely different from any other kind of speech. These words give voice to a deep conviction that the God of Jesus Christ speaks when the Scriptures are opened in the power of the Holy Spirit.
"The preacher opens the Bible and interprets the word of God. This is a mystery, a miracle that takes place. The very grace of God, who comes down from heaven into our midst and speaks to us, knocks to our door, asks questions, warns us, threatens us, and makes us joyful again and free and sure. This is the work of the Holy Spirit, who acts when the Scriptures are opened in the church and brought to life, making God present while the world continues on with its busyness, running after fads, excitement and entertainment, yet not knowing that in the church, time and eternity meet through the Word." 
In preaching, both then and now, God asks something of the church that is both strange and astonishing; “be reconciled to God, receive God’s kingdom, take heaven as a gift … This is a strange glory, the glory of this God who comes to us as one who is poor, in order to win our hearts.” 
The message and ministry of reconciliation means the church is called to the obedience of faith in Christ who is himself the source, content and focus of preaching. To preach this message, God’s message of reconciliation in Christ, and to preach in this manner, as an ambassador making an appeal on behalf of Christ, represented a decisive shift from familiar “modern” ways of preaching that privilege humanity over God. The end or purpose of preaching is to build up and form the church in the Word, an eschatological act which makes Christ’s presence visible in the world. Bonhoeffer refused to concede the darkening political conditions in Hitler’s Germany were the “end” or final word in God’s work. Returning to 2 Corinthians 5 on Repentance Day, he gave voice to God’s urgent appeal for the church to repent.
"Turn back! Turn back! The whole Bible calls to us joyfully. Turn back! Where? To the everlasting mercy of God who never leaves us, whose heart breaks because of us; the God who created and loved us beyond all, measure.”