What does Acts 21:27 mean?
During Paul's third missionary journey, he traveled through Galatia, the province in central modern-day Turkey. He eventually settled in Ephesus, in the province of Asia in western Turkey. He spent three years in Ephesus, establishing and building up a church. When a protest caused by disgruntled shrine craftsmen turned into a riot, Paul left and toured the churches he had established previously in Macedonia and Greece (Acts 19—20).When he returned to Jerusalem, representatives from these churches came along to bring the money they had collected for the church in Jerusalem (Acts 20:4; Romans 15:26). Paul accompanied the men to James and the elders to report on his work. The elders were happy that Paul had seen such success among the Gentiles. Unfortunately, they were also concerned about rumors that he had abandoned the Mosaic law and taught other Jewish Christians to do the same. To prove his continued Jewishness, Paul agreed to help four men complete their vow.
The text doesn't indicate what type of vow is meant, but it's most likely a Nazirite vow. This is a voluntary oath, taken by men and women, to dedicate one's life to God for a period. That the rite takes seven days leads some to believe that the vow had been interrupted unexpectedly, most likely because the men encountered a corpse. This would mean they needed to finish the eight-day ceremony that would cleanse them and reset the timeframe. That the Bible says it would take seven days and Luke says eight could be due to a difference in how Jews and Greeks measure days.
However, this may be the completion of the vow. The elders ask Paul to cover the men's expenses; if this is a vow reset, the sacrifice is two turtledoves or two pigeons for each man—a negligible amount. If the men are completing the vow, Paul will have to provide eight lambs, four rams, bread, oil, grain, and wine. This seems a more likely demonstration of Paul's faithfulness to the Law (Numbers 6:1–21).
One of the men accompanying Paul is Trophimus, a Gentile from Ephesus. Sometime during the week, Jews from Asia see Paul with Trophimus in the city. When they later see Paul at the temple, they erroneously conclude Paul has brought the Gentile into the temple. This not only breaks the Mosaic law, but it also defiles the temple. Defiling or insulting an "approved" religion also breaks Roman law. The elders of the church had wanted Paul to fulfill the men's requirements to prove he is a faithful Jew; he doesn't even get the chance. Paul's accusers inflame the crowd who attempts to beat him to death. Paul is only rescued when the Roman tribune arrests him (Acts 21:28–36).