There were Jewish Christians in Rome

As I have suggested earlier, there must be Jewish Christians in Rome. Acts of the Apostles describes Paul's house-arrest in Rome, waiting to appeal to Caesar. He met local leaders of the Jews (Acts 28:17) and gathered a great crowd around him to listen to his preaching. Some Jews were converted while others remained skeptical (Acts 28:23-24).
Paul was not the first to preach to the Jews in Rome. If Paul could convert some, I am sure others before him, probably those who fled from his previous persecutions, were able to convert some Jews who would be reading this Epistle to the Romans. Here in Romans 2, we find clear references to Jewish Christians in the Roman Church. Rome was the capital of the Roman Empire. There must be Jewish businessmen as well as Jewish Christians from all over the world. Jewish Christians together with Gentile Christians formed the Christian Church in Rome. Therefore, the audience of the Epistle to the Romans must consist of a mixture of Jewish and Gentile Christians.
From the observation above, it is reasonable to believe that Romans 2 addresses the Jewish section of the Christian Church in Rome. Perhaps Paul wrote to them because it was the Jewish Christians who passed judgment on Gentile non-believers. So, when Paul wrote "to the Jews first, and also to the Gentiles" twice (Romans 2:9-10), he was encouraging/warning the Jewish Christians that they would be the first to receive glory/punishment if they did good/evil things. God does not care whether they were Jews or Gentiles (Romans 2:11).

The Jews had the advantage of possessing/knowing the Law of God. However, such knowledge is of no use if they did not practise it.
For not the hearers of the law are just before God, but the doers of the law shall be justified (Romans 2:13)
Martin Luther would be very much disappointed to hear that doers of the law shall be justified. His teaching of "sola fide"  is refuted because faith is not the only way to attain justification. Keeping the law can also attain justification. Luther could not have missed this passage, nor could people cover this text up successfully.  Luther simply bypasses it, does not mention it.
God is fair. He would not let the Gentiles suffer the disadvantage of not having a Moses to hand down His Law to them. Still, they were able to follow their conscience and continued to prepare themselves to meet God's judgment at the end of the world (Romans 2:15-16).
Here, Paul brilliantly set out the functions of our conscience: as God's Law written in our hearts, conscience accuses and excuses. Our conscience would condemn us and make us feel guilty (accuses) if we do not follow the advice it offers us (excuse) and make moral mistakes.

Then Paul speaks once more heart to heart with his fellow Jews.
Behold, thou art called a Jew, and restest in the law, and makest thy boast of God,
And knowest his will, and approvest the things that are more excellent, being instructed out of the law;
And art confident that thou thyself art a guide of the blind, a light of them which are in darkness,
An instructor of the foolish, a teacher of babes, which hast the form of knowledge and of the truth in the law.
Thou therefore which teachest another, teachest thou not thyself? thou that preachest a man should not steal, dost thou steal?
Thou that sayest a man should not commit adultery, dost thou commit adultery? thou that abhorrest idols, dost thou commit sacrilege?
Thou that makest thy boast of the law, through breaking the law dishonourest thou God? (Romans 2:17-23)
Is it a caricature of all the Jews, or just the Pharisees who were portrayed hypocrites in the gospels?
Did Paul write from his personal experiences or what he had met among the Roman Jews?
Then, he turned to touch the nerves of the Jews --- circumcision! From this, Paul concludes that the outside does not count. Only the inside counts.
For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh:
But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God (Romans 2:28-29).

Dear Lord, I do not dare to show my inside which is very ugly. I am a hypocrite. I do not dare to express my displeasure which may turn wild out of control. I am sorry for being angry with Brenda this morning. Forgive me, Lord. Amen.