Shared ground
Luke uses these verses as travel markers: Paul leaves Corinth, moves through key ports and cities, and begins another round of strengthening already-formed groups of believers. The narrative emphasizes real movement (ports, sailing, roads) and relational continuity (Priscilla and Aquila travel with Paul and then remain in Ephesus).
Several explicit claims are clear in the text: Paul departs “after many days,” he travels with Priscilla and Aquila, he cuts his hair at Cenchreae in connection with a vow, he has a brief synagogue conversation in Ephesus, he refuses to stay longer, and he later returns to Antioch before traveling on through Galatia and Phrygia.
The passage also presents two planning constraints in Paul’s movements: a time-sensitive commitment (a “coming feast” linked to Jerusalem) and a humility about outcomes (“if God wills”). These are stated as reasons for his schedule rather than as a full explanation of his theology.
Where interpretation differs (only where needed)
1) Whose vow was involved (v. 18). Most readers take the vow to belong to Paul, since he is the subject who cuts his hair. Others think the grammar could allow the vow to belong to someone else in the travel party, because the scene mentions multiple people and the vow is only briefly noted.
2) Which feast is meant (v. 21). Some think it points to a specific major pilgrimage feast in Jerusalem (such as Passover or Pentecost), which would explain urgency. Others say Luke may be intentionally general, using “the coming feast” mainly as a timing marker without telling which one.
3) Which “assembly” Paul greets (v. 22). Many understand this as the believers in Jerusalem, since “went up” often describes going up to Jerusalem and because the prior line mentions a feast there. Others argue it could refer to believers in Caesarea or another nearby gathering, since Caesarea is explicitly named as the landing point.
4) Whether Paul’s Jerusalem-feast sentence is original (v. 21). Some manuscripts do not include the line about needing to keep the feast in Jerusalem. If that shorter wording is followed, Paul still intends to leave and still says he hopes to return if God wills, but the explicit Jerusalem-feast motive is less direct.
Why the disagreement exists
The uncertainties come from how briefly Luke reports these details. The vow note is a one-line comment with limited context. The feast is unnamed. The “assembly” is referenced without identifying which city it is in. And the wording in v. 21 differs across manuscript lines, which affects how strongly the Jerusalem connection is stated.
What this passage clearly contributes
These verses link two phases of the story by showing that Paul’s mission includes both initiating new work and maintaining existing communities (“strengthening all the disciples”). They also show Paul’s ministry pattern: engaging synagogues when possible, traveling with co-workers who can remain behind, and making plans that are both time-aware (feast/travel windows) and open-ended (“if God wills”). The section functions as a hinge: Ephesus is previewed briefly now, setting up fuller developments later (compare Acts 19:1).