In his letter to the Romans, how does Paul justify that the Jewish people should accept Christ?

By revealing to the Jews the purpose of the law. The purpose of the law was to bring conviction and prove guilt, not for justification. The Jews could never obtain the righteousness of God by works. Paul also reveals that all have sinned, thus only way to be justified for both the Jews and gentiles is through faith in Jesus Christ.

Because the law cannot be satisfied, they were doing the law to be in God’s grace not out of faith, and we know that nobody can by personal means meet God’s standards is through sanctification that we start to change to a lifestyle more incline to God’s will.
Paul also explained that while the law was righteous, it was a tool sin used to create more sin, because it called to our flesh and that natural desire of rebellion we have from Adam.

Paul explains in no uncertain terms that the law’s purpose was to bring people to a saving knowledge of Christ, not to do the actual saving through works. Thus, the Jews need a savior as does the rest of humanity, and that Savior is Jesus Himself!

Paul says the Jews are in the same boat as everyone else , even though they claimed to have a special relationship with God, Paul explains that we have all sinned and fallen short of the Glory of God.so Paul says we all need a redeemer, someone to buy us back from sin and death.

In the Book of Romans (Romans 1:16) is the statement, “to the Jews first.” The Jewish people are God’s chosen people. Through the Jewish people, God demonstrated His love and holiness to the world. Through the Jewish people came the Prophets, God’s promises including the Christ.

Paul pointed out that the Jews were the same as all people even though they were the “chosen ones”, that no one is righteous and Christ is the one who sets every Christian free from sin through the price he paid on the cross. We need his help as we can’t please God on our own. The OT told of the coming of a Messiah.

The written law in the Old Testament isn’t in conflict with the moral actions of all Christians. When we sin we are at odds with God and we are separated from Him. In lee of sacrificing an animal, Christ has already paid the price of our sins.