Note 7 at 1Co 9:20: Paul was a physical descendant of Abraham, and this made him a natural Jew. Yet there was much more to being a Jew than a person's DNA (see note 10 at Joh 8:33). Paul made it clear that being a true Jew was a matter of the heart (see note 1 at Ro 2:28 and note 2 at Ro 2:29).

So, when Paul said he became as a Jew to reach the Jews, he was saying he used his knowledge of Jewish laws and customs to relate to non-Christian Jews. He lived in a manner in which his physical actions would not "turn off" the Jews to his message. If people rejected the Gospel, so be it, but Paul did not want to be the one who offended.

He took a vow and purified himself and others in the temple to show his good faith to the Jews (Ac 21:23-26). He gave place to his weaker brethren in nonessential physical things, but he never compromised the message.

The application of this in our modern world is this: If people, such as Mormons or Jehovah's Witnesses, come to our doors, we should know something about where they are coming from so that we can relate to them and be proper witnesses. Also, our standard of holiness should be such that they will not reject our Gospel before hearing it, because of our actions.

We should not live lifestyles that offend others. We should be moderate in our dress and actions so that others will be able to listen to our message.

Note 8 at 1Co 9:20: This is a very revealing statement. Paul was not under the Law! He said this on other occasions (Ro 6:14-15; Ga 3:23-25, 4:21, and 5:18), but this was a very radical statement to the Jewish minds of his day, just as it is to the religious minds of our day. He did say in the next verse that he was "under the law to Christ" (1Co 9:21, see note 10 at that verse).