What does Acts 21:26 mean?
To prove to legalistic Jewish Christians that Paul still reveres the Mosaic law, the elders of the church in Jerusalem have asked him to help four men complete what was likely a Nazirite vow. A Nazirite vow is a voluntary, temporary commitment to total dedication to God. The adherents, in this case men, abstain from anything made from grapes and do not cut their hair. At the end of their vow, they must present a sacrifice and shave their heads. If they become unclean, particularly by accidentally contacting a corpse, they must go through an eight-day cleansing ritual and restart their time (Numbers 6:1–21).Since the men's purification takes seven days (Acts 21:27), some scholars think this is a reset—the difference between eight and seven days may be because Luke counts days in the Greek way and not the Hebrew way. But the offering for a reset is merely two birds each; eight birds wouldn't cost much. The offering to fulfill the vow includes a female lamb, a male lamb, a ram, unleavened bread, loaves of bread, crackers, oil, and a grain and drink offering. Such an expense for four men would go a long way in proving Paul's devotion to the Law and be a sacrifice for someone who supports himself on the field (Acts 18:2–3; 1 Corinthians 9:4–7; 1 Thessalonians 2:9).
Paul arrived in Jerusalem with several men—Jews and Gentiles—who came from modern-day Turkey, Greece, and Macedonia. He presents money collected by their home churches for the church in Jerusalem (Acts 20:4). One of these is Trophimus from the city of Ephesus in Asia, the large district in western Turkey. At some point in this week, Jews from Asia see Paul with Trophimus in the city. When they later see Paul in the temple, they assume Trophimus is with him. Legally, Trophimus is allowed to be outside the temple, in the court of Gentiles. To bring an uncircumcised Gentile into the temple is against the Mosaic law and, since it would be the defilement of a religious structure, it is also against the Roman law. The false witnesses accuse Paul as he stands amidst the temple crowd. The people beat him, and the tribune of the Roman outpost arrests him (Acts 21:27–36).