The first sermon was an exposition

Something happens in Jerusalem that has no category. A sound like wind, fire that separates and rests on people, and a hundred and twenty ordinary Galileans speaking languages they never learned, heard by pilgrims from fifteen named regions.

A crowd gathers. Some are amazed. Some say they are drunk.

And Peter — who three months earlier could not hold his ground against a servant girl by a fire — stands up with the eleven, raises his voice, and does the single most predictable thing available to him.

He opens the Bible.

Everyone in that square had just seen something none of them could explain. Peter’s first move is to tell them it had already been explained, eight hundred years earlier, by a prophet whose scroll they owned.

This is what was spoken by the prophet Joel. The most supernatural morning in the history of the church, and the first apostolic response to it is a text.

Work through what the sermon actually consists of.

He quotes Joel 2 at length, to explain the phenomenon. He quotes Psalm 16, to argue that David was speaking of someone whose body would not see decay. He quotes Psalm 110, to explain the ascension. Three Old Testament passages, expounded, in a sermon of about twenty-five verses.

Peter’s own contribution is the connective tissue — this is that, and God has raised this Jesus, and we are all witnesses of it. Eyewitness testimony joined to Scripture. That is the whole method.

He does not build on the experience. He explains it, from a book, and then moves off it as fast as he can toward Christ. Within a few verses the tongues have dropped out of the sermon entirely and the subject is a man attested by God, delivered up, crucified, and raised.

Cut to the heart. That is the same picture the volume met in Hebrews — the word getting past the ribs.

Three thousand were added that day, and Luke tells us what they devoted themselves to afterward: the apostles’ teaching, fellowship, breaking of bread and prayer. Teaching is named first.

There is also the matter of what Peter now does with a text he had heard used before. On the road to Emmaus and in that upper room, Christ had opened the Scriptures and opened their minds. Two months later Peter is doing it in public, unaided, under pressure. The teaching took.

The church was born on a day of overwhelming supernatural evidence, and its first act was to explain a passage of Scripture to a confused crowd. Everything since has either kept that order or drifted from it.

The Joel citation is longer than most readers notice — Joel 2:28–32 in full, including the sun turned to darkness and the moon to blood. Peter applies the passage to the day he is standing in without explaining the unfulfilled portions, which has occupied interpreters ever since and should be admitted rather than smoothed over.

The Psalm 16 argument turns on a single point: David died and was buried and his tomb is with us to this day, so the psalm cannot be about him. Peter reasons from the biography of the author back to the meaning of the text — an ordinary interpretive move, made in public, to a hostile crowd.

Psalm 110:1 is the most frequently quoted Old Testament verse in the New Testament. Jesus used it Himself against the Pharisees, and it turns on the distinction between two lords in a single sentence.

Note the audience. Luke lists devout Jews from every nation under heaven, naming regions from Parthia to Rome. These were people who knew the Scriptures Peter was quoting; the sermon assumes a biblically literate crowd and argues accordingly.

Peter’s conclusion is the sharpest sentence in the sermon: God has made this Jesus, whom you crucified, both Lord and Christ. He does not soften the second person plural. The crowd’s response — what shall we do? — comes after being told plainly what they had done.

It is worth counting the quotations by volume rather than number. Of roughly twenty-five verses of sermon, well over a third is direct Old Testament citation. The proportion is the point: the apostolic method was exposition with testimony attached, not testimony with a verse attached.

Look it upG611 ἀποφθέγγομαι apophthengomai, to speak out, declare · G2660 κατανύσσω katanusso, to pierce or cut through · G3142 μάρτυς martus, witness · G1322 διδαχή didache, teaching

Then compare Stephen’s speech in Acts 7 and Paul’s in Acts 13, both of which are extended retellings of the Old Testament. The pattern holds across three different preachers.

Where this touchesActs 2:14–42 · Joel 2:28–32 · Psalm 16:8–11 · Psalm 110:1 · Acts 7 · Acts 13:16–41 · Hebrews 4:12 (Week Four, Day Two). The Emmaus exposition was last week’s Day One.