Counsel from Robert Lewis Dabney on the need for preaching to be both doctrinal and practical:
It is the duty of the preacher so to establish the dogmas of the faith in the understandings of the people, that they shall not remain abstract dogmas, but shall reveal their close bearing upon the life. It was a golden maxim of the Protestant fathers, that “doctrines must be preached practically and duties doctrinally.”
The reasons for doctrinal preaching thus defined, may be all traced to the principle that truth is in order to godliness. Sanctification is by the truth. Man is a reasoning creature, and the word and Spirit of God deal with him in conformity with this rational nature. All those emotions and volitions, which have right moral character, are prompted in man by intelligent motives. To say that one has no reason for his volitions, is to describe them as either criminal or merely animal. In the things of God man only feels as he sees, and because he sees with his mind. A moment’s consideration of these obvious facts will convince you that there cannot be, in the nature of the case, any other instrumentality to be used by creatures for inculcating religion and procuring right feeling and action, than that which begins by informing the understanding. The truth, as seen in the light of evidence, is the only possible object of rational emotions. From this point of view, we easily understand how unreasonable are the notions and demands of those good people who decry didactic preaching. “Such discourses,” they say, “are dry and repulsive. They give us merely theology in its bare bones. They inflate the head with conceit without warming the heart. The aim of Christianity is but to make men feel and act right. Let the preacher then aim directly at the heart, producing right feeling, all will be accomplished.” Now, I might assent to the latter statements, and yet raise the question, How shall the heart be reached, except through the head? How can a rational creature be made to feel intelligently, unless we cause his reason to apprehend that which may be the object of rational feeling? If any affection is produced otherwise, it must be merely animal or else evil. Heat without light is blind, as light without heat is cold. The Sun of Righteousness, like the natural luminary, becomes the fountain of life in his appropriate realm by given heat through light. (Sacred Rhetoric, pp. 52-53)