“You see, brother, how many thousands there are among the Jews of those who have believed. They are all zealous for the law …” (v20). Thousands of Jews had believed in Jesus, and they were also “zealous” for their own Jewish traditions. Apparently, these Jewish believers were worried that Paul was being disloyal to his cultural background (v21). Paul pacified them by going through a ritual vow (v26), but then other people accused him of “defiling” the Temple by bringing in Greek friends.
Paul’s mission to evangelize the Gentiles cost him friendships and provoked misunderstanding. Yet he “counted everything as loss” – risked it all – for the sake of knowing Christ and being His witness.