Sadly, many of today’s Jews profess godliness but don’t embrace the Scriptures as we presume they do. Therefore, it is often difficult to reason with them about Jesus being the Messiah. This is why it is imperative to ask a Jew if he has kept the Law of Moses—to "shut" him up under the Law (Galatians 3:23) and strip him of his self- righteousness. The Law will show him his need of a Savior and become a "schoolmaster" to bring him to Christ (Galatians 3:24), as happened to Paul, Nicodemus, and Nathaniel. It was the Law that brought 3,000 Jews to the foot of the cross on the Day of Pentecost. Without it they would not have known that they had sinned (Romans 7:7), and therefore would not have seen their need of the Savior. See Luke 18:20 footnote for how to use the Law in evangelism.
Seriously. This incenses me. It often is "difficult to reason with them" ... well geepers! Sorry we made it so *hard* for you to convert us all into the truth and light of Christianity. Then they say you should ask the Jew whether he's devout, "to 'shut' him up under the Law and strip him of his self-righteousness." UGH. Seriously. WTF? I can't even create coherent thoughts, because this is downright offensive. For more fun go here: Way of the Master.