Two styles of preaching
The two basic styles of preaching are the ad populem and the ad clarem styles.
The former is what is most properly and strictly the sermon as is found upon the lips of the prophets, the apostles, Christ Himself, and great figures in the history of the church as were the Reformers. This type of preaching is addressed to the general public, it does not aim at a polished style as such, but is addressed to the heart, to the very conscience and soul of the hearers.
In fact, from ancient times the sermon was known as the homily (Greek, homilia, a sermon or discourse upon some point of religion, delivered in a plain manner, so as to be easily understood by the common people. The Greek word signifies a familiar discourse, like the Latin sermo. Discourses delivered to the people of God followed this guide-lines, to intimate that they were not harangues, or matters of ostentation and flourish, like those of profane orators, but familiar and useful discourses, as of a master to his disciples, or a father to his children.
Presented in such a condensed and abbreviated mode, the sermons of Paul and his fellow-apostles (in the Acts especially), we may still see what a sermon properly so-called should sound like. This was Paul's avowed ambition, to preach Christ and Him crucified, "not with enticing words of man's wisdom, but in demonstration of the Spirit and of power" (1 Corinthians 2:4). And there is a specific purpose why we should adopt such a preaching stance: "That your faith should not be in the wisdom of men, but in the power of God" (v.5).
Though both content and delivery are important in a sermon, people should be attracted to our churches by the content (primarily), and only secondarily by the delivery. The latter is subordinate to the former.
In the other style of preaching, the ad clarem, the reverse tends to hold true. This is the style of preaching as so often flourishes in places of education, in universities, and seminaries. This style developed and became the norm during medieval Scholasticism. It is a lecture-type of sermon, with strict and logical divisions and subdivisions of the talk.
This was rejected by the Reformers, especially Luther and Calvin. To read their sermons is so refreshing; they sound lively and practical and addressed to the heart.
Though I do not mean to cast a shadow on the Puritans, they reverted to the ad clarem type of preaching. Though their content in preaching was sound, it was often presented in a stiff and rigid way, as if a professor of theology was addressing another professor of theology.
It is evident to me that the ad clarem style has the upper-hand today. This is sad. Is it because the pastors generally desire to be accounted as learned men, because they want to leave an impression of scholarship?
The church, consisting mostly of poor and simple people, would be much profited by a return to a prophetic type of preaching, the ad populem, where preaching would be an interaction between preacher and people: a dying man preaching to dying men, urgently, solemnly, simply, powerfully.