Lecture 1-6: The Purpose of Preaching (2) — Building the Church and Shaping Lives

3.1 A construction word, not a decoration word

The Greek verb behind "building up," oikodomeō (οἰκοδομέω), is a construction term — it pictures a wall going up brick by brick, not a single dramatic event. Paul reaches for this word repeatedly when he talks about the church's growth, and Ephesians 4:11-12 uses it to explain why God gave the church people gifted specifically to teach and shepherd it: "for the perfecting of the saints... to the building up of the body of Christ."

Preaching's place in this picture is direct. Preaching is the most regular, most sustained channel through which the teaching and shepherding gift named in Ephesians 4:11 is actually exercised, week after week, over years. This has a sobering implication worth stating plainly: no single sermon completes a church. A sermon that tries to accomplish everything, to say the final word on a subject in one sitting, misunderstands the nature of the work it belongs to. Preaching is cumulative labor, brick by brick, and its fruit is usually visible only across a long stretch of time — which is exactly why chapter 13 of this course, on sustaining a preaching ministry across years rather than single Sundays, matters as much as any chapter on a single sermon's construction.

3.2 Two dimensions of building up: the person and the community

Building up happens on two levels at once, and both matter.

The first is personal sanctification. Romans 12:2 states the pattern directly: "Don't be conformed to this world, but be transformed by the renewing of your mind." Preaching aims at exactly this in each individual hearer — a transformation of how a person thinks, feels, and lives, moving toward the character of Christ.

The second is communal maturity. Ephesians 4:13 names the same goal at the level of the whole church: "until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a full grown man, to the measure of the stature of the fullness of Christ." Preaching does more than change individuals one at a time; over time it forms a congregation into something more than a collection of separately growing people — a single body maturing together, shaped by having heard the same word, responded to it, and obeyed it side by side.

These two dimensions cannot be pulled apart. A congregation does not mature as a body if its individual members are not being changed; sanctification that never shows up communally has stalled somewhere short of its goal. And an individual's sanctification does not happen in isolation either — it depends on the shared life of worship, the ordinances, and fellowship that only a gathered community provides. Preaching serves both dimensions in the same act, because it is delivered to individuals who are, at the same moment, gathered as one body.

3.3 Preaching as a means of grace

2 Thessalonians 2:13 traces salvation itself to "sanctification of the Spirit and belief in the truth" — and "the truth" here is the preached word. The Reformed tradition has long described preaching as one of the "means of grace": an ordinary channel the Spirit uses to make people holy, alongside the sacraments and prayer. This is a strong claim, worth stating precisely so it is not mistaken for something smaller. Preaching is not merely information transfer, and it is not merely motivational encouragement. It is one of the actual instruments the Spirit uses to change people — which returns this lecture directly to the previous chapter's argument about illumination and unction: the Spirit who illumines the preacher in study and empowers the sermon in delivery is the same Spirit who then uses that delivered word as an instrument of sanctification in the hearer.

3.4 No preacher carries this alone

Ephesians 4:11-12 is worth reading a second time for something easy to miss on a first pass: the gifts named there exist "for the perfecting of the saints, to the work of serving" — meaning the shepherd-teacher's job is not to perform every act of ministry personally, but to equip the whole congregation to serve. A preacher who imagines that building up the church depends entirely on their own sermons, with no other ministry in the congregation contributing anything of comparable weight, has misread this passage. Preaching is the primary channel for the teaching and shepherding gift, not the entirety of how a church is built. This does not lower preaching's importance; it correctly locates that importance within a larger body of ministry the preacher's own preaching exists to equip.

3.5 One theology, five pillars

This chapter now closes where the introduction to this course promised it would: with a single, connected theological account of what preaching is, rather than five unrelated observations that happened to share a syllabus.

God is a God who speaks — that is revelation, and lecture 1-1 built the paradox this creates: fully human words functioning as the word of God. The center of everything God has spoken is the good news about Christ — that is the kerygma, and 1-2 showed why no sermon on any text can leave it out entirely. That speech reaches every generation as a finished, sufficient text, and a preacher's authority rises and falls with fidelity to it — that was 1-3's argument, built on Peter pointing past his own experience to "the more sure word of prophecy." None of this reaches a hearer without the Spirit, who illumines a preacher's study and carries a sermon's delivery — 1-4's distinction between illumination and unction. And all of it serves an end that is not the preacher's own: hearers brought into a personal knowledge of God (1-5) and a church built up, member by member, into the maturity of Christ (1-6, this lecture).

Follow that chain back to its first link and the chapter's whole argument comes into view. A sermon's right to command a hearer's life does not originate in the preacher's insight, however carefully studied, and it does not originate in how well the sermon answers a congregation's felt needs, however real those needs are. Preaching begins outside the preacher. It begins in revelation — in the fact that God has spoken at all — and everything this chapter has argued, from the paradox of human words carrying divine authority to the Spirit's work in illumination and unction to the church slowly being built up brick by brick, depends entirely on that one fact holding. Take revelation away, and a sermon is left with nothing but a person's opinion about an old book, however sincerely delivered. Chapters 2 and 3, which follow, will trace how the church has lived out this conviction across its history and what it asks of the person who preaches — but neither chapter can replace what this one has established: that a sermon's authority was never the preacher's to begin with.