The sermon…is the property of the church in the custody of the pastor. Both qualifiers are important. Because the sermon does not belong to the preacher, but to the whole church, the preacher will try to see to it that, on a given Sunday morning, the witness of the whole church is heard, not simply the preacher’s own biases and prejudices. But because the sermon is placed in the custody of the pastor, it will at the same time be a personal statement, a kind of “testimony”: This is how I hear the Spirit speaking to me in the Scripture for the day.
Furthermore, the sermon on Sunday morning is set in the context of the church’s public liturgy. It is one part of a larger public offering of praise and thanksgiving – part of a meeting with the Lord of life and with one another in the Christian family. The sermon of course brings God’s Word to bear upon our lives in contemporary terms; it mediates between God and His world; it provides a “mask” through which the hidden God is revealed in His judgment and His grace, today, in this place, among these people.
Rev. Paul F. Bosch, The Sermon As Part of the Liturgy, page 19