From Sidney Greidanus’ Preaching Christ from the Old Testament:
The object and content of preaching is Christ, the Word in which the Father expresses Himself and communicates His will to man. (Domenico Grasso, Roman Catholic)
Ministers are commissioned and ordained in the church precisely to preach the Word of God. They are given some fixed terms of reference– namely, the gospel of Jesus Christ– and they are committed to this sole and perennial message. (Georges Florovsky, Eastern Orthodox)
It is necessary that the sermon be Christocentric, have no one and nothing else for its centre and content than Christ Jesus. (M. Reu, Lutheran)
In expositing Scripture for the congregation, the preacher … must show that there is a way to the center even from the farthest point on the periphery. For a sermon without Christ is no sermon. (T. Hoekstra)
Preach Christ, always and everywhere. He is the whole gospel. His person, offices, and work must be our one great, all-comprehending theme. (Charles Spurgeon)