When Paul arrived in Jerusalem he was warmly greeted, and the next day he reported to James and the elders of the church about his adventures among the Gentiles. They received his report with joy, and no doubt were also happy to learn that he was not guilty of the things that were being said about him in Jerusalem, for it would seem that many Jewish Christians had been told that Paul was telling Jews in faraway places that they should not observe the Law of Moses.
We know from Paul’s letters that he often spoke highly about the law, we also know that he often spoke harshly about Jews who insisted that Gentile believers be circumcised, and that Paul himself claimed that he was not under the law as a Christian, but that he observed the law when dealing with Jews, and not when dealing only with gentiles. At no point in his letters or recorded remarks does he advise Jewish Christians not to live according to the Law.
As you see, there are some fairly fine lines here, and one might understand how a Jewish Christian might misunderstand Paul’s position… especially when his position was deliberately misrepresented by those who sought to discredit him.
James proposed a solution to this problem: Paul could join in a purification rite which would be a very public demonstration that Paul had not rejected Jewish law or custom; surely this would convince anyone who harbored a genuine misunderstanding about Paul’s teaching that he had not done the things he had been accused of; Paul quickly agreed to this and participated, in accordance with Jewish practice.
What follows demonstrates to us very clearly that there was something much more sinister afoot than a simple misunderstanding…