It has been and continues to be the tradition of the United Reformed Churches (URC) to have a catechism sermon during the evening service. This involves an exposition of (usually) the Heidelberg Catechism, as it is conveniently separated into 52 Lord’s Days and covers the full (or at least the most important) range of doctrine that one finds in the Bible, and specifically the New Testament. I like to call the catechism service the URC’s version of the topical sermon. In the book The Preacher and Preaching, Donald Macleod has some interesting thoughts on the subject. He writes,
“Should we preach on catechisms or confessions as such? Only in the most exceptional circumstances. Our mandate is to preach the Word. To resort instead to expounding a human document is to confuse our people by blurring the distinction between what is normative revelation and what is to be judged by revelation. Even when creeds are inerrant (a claim that can be made for the Apostles Creed, for example), their proportion, balance, and selections of topics will not be that of Scripture. Furthermore, confessions and catechisms present doctrine abstracted from its existential context—the life-situation of Scripture—and thus obscure its practical relevance or tempt us not to apply it at all” (emphasis mine).
I think Macleod brings up some great points and distinctions. While we believe that the doctrines expounded by our confessions do present the reality and truth of the Word of God, they are subservient to the Word of God. Confessions can err, and often do not contain the full reality of a doctrine. This is because they are meant to be summaries of doctrinal truth, and that is good as far as it goes. But only God’s Word is infallible and inerrant, and will not be out of proportion or balance.
Another great point Macleod brings up is that when a preacher expounds the Catechism during a sermon, the doctrine contained within it is pulled from its position in Scripture, or the way it is taught in Scripture. It is more useful and relevant to preach through Scripture, to see the doctrine arise out of both didactic and narrative portions, for then we see why the doctrine matters and how it can apply to our lives. If the Catechism presents God’s truth in summary form, then preaching through Scripture will have the same effect. And the Scripture alone is God breathed.