In Acts 21 we have an episode in the life of Paul that is confusing to many people. Paul has been in Macedonia, and is traveling by ship to Jerusalem. The festival of Passover is past, and Paul is trying to reach Jerusalem by Pentecost, seven weeks later. Pentecost (Shavuot) is one of the festivals that Jewish men are to go to Jerusalem for (Deu. 16:16), and Paul missed going there for Passover because of his travels.
Paul suspected that he might run into trouble in Jerusalem (20:22), and stated that none of those from Ephesus would see his face again (20:25). In Caesarea a prophet told him that he would be bound and handed over to the Gentiles. But Paul was convinced that God wanted him to go to Jerusalem.
When Paul arrived in Jerusalem, he was greeted warmly. Then he went to see James and the elders, who told him that there was a false rumor about him going around. First they point out that there are thousands of Jews there who have believed in Jesus, and all of them are zealous for the law. Then they reveal the rumor that is being spread about him.
Some people have been claiming that Paul has been teaching Jews in the diaspora that they no longer should circumcise their children or live according to God’s law. Where in the world could they have gotten that idea? They probably got it from the same place that many today have gotten the same impression of Paul, from misunderstanding some of Paul’s early writings, like the epistle to the Galatians.
But Paul will have none of it. He eagerly accepts the suggestion of the elders that he demonstrate his fealty to the law by taking on the expenses of some men who are in the process of concluding a Nazirite vow (Num. 6). Paul himself had taken a similar vow a year or two earlier (Acts 18:18), and he was happy to participate. All involved agreed that this would show that Paul was living in obedience to the law, and that there was no truth in the rumors (21:24).
So Paul purified himself along with these men, and went to the temple with them to arrange for the finalizing of the ceremony. This passage is a problem for many Christians today because they have been taught that Paul was opposed to keeping the law, and that he was being a hypocrite by affirming it like this. When I was in college, I heard my own father preach on this passage, and he was convinced that Paul was in error to do this. I agreed with him at the time, since that is what I had been taught as well. But in the years since, through studying the New Testament, I’ve come to some very different conclusions.
The story goes on to tell how several days later Paul was recognized in the temple by some Jews from Asia, and they made the same false accusation, that he had been teaching aginst the temple and the law and the Jewish people. Paul is arrested, and over the next several chapters he strenuously denies these charges many times.
But the main point to be made here is that Paul, as well as the believers in Jerusalem, was “zealous for the law”. It comprised the commands that God had given to his people for living to please him.
The elders admitted that Gentile believers were given a little bit of leeway, as they got used to keeping the law. But Jewish believers, as Paul himself, were to follow God’s commands for living, through the power of the Holy Spirit.