(The previous entry concerning TPDS may be found here: https://memoirandremains.wordpress.com/2013/03/01/know-to-whom-you-preach/
As Broadus (A Treatise on the Preparation and Delivery of Sermons) notes, a sermon must be bound by the text:
TO interpret and apply his text in accordance with its real meaning, is one of the preacher’s most sacred duties. He stands before the people for the very purpose of teaching and exhorting them out of the Word of God. He announces a particular passage of God’s Word as his text with the distinctly implied understanding that from this his sermon will be drawn—if not always its various thoughts, yet certainly its general subject. … But using a text, and undertaking to develop and apply its teachings, he is solemnly bound to represent the text as meaning precisely what it does mean.
This would seem to be a truism. But it is often and grievously violated.
It seems strange that preacher would not consider himself bound by the text, and yet as Broadus notes, “it is often and grievously violated.”
Now, his diversion may not be from malicious motives (it often is not). However, by substituting his own “good” idea for the text, the preacher places himself above the text and thus above God’s wisdom. He seeks to “improve” God’s exhortations. By so doing, the preacher lays a burden upon the congregation which God did not lay; or he exhorts the congregation to an appropriate goal by an inappropriate means (and thus calls them to work with providing God’s help).
“That is a distorted ministry which deals in any large proportion with subjects which are not logically presented in the Scriptures. It is not a biblical ministry” (TPDS, 34; quoting Phelps).