After Paul's introduction to Romans, he stated a theme for the entire letter.
Romans 1:16-17 (KJV)
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.
Paul began by declaring that he was not ashamed of the gospel of Messiah (verse 16). Considering all that he went through, he obviously was speaking the truth.
2 Corinthians 11:25 (KJV)
Thrice was I beaten with rods, once was I stoned, thrice I suffered shipwreck, a night and a day I have been in the deep;
Can we say the same? Or do we act like we're ashamed of the gospel? Do we keep silent for fear of rejection or ridicule? Are we willing to face ill treatment or even death because of being open about our faith? What is that gospel worth to us?
The reason that Paul was able to stand up for the gospel of Messiah was because it is the powerful means by which mankind can be saved. Paul also indicated that that powerful means is available to those who believe (or trust) in Messiah. He stated this same concept in Ephesians.
Ephesians 2:8 (KJV)
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
In a manner of speaking, the gospel of Messiah is the message of grace. The Son of God, Yeshua, came to earth in the flesh, suffered and died on the cross, to pay the penalty for the sins of those who would trust in Him.
The gospel of Messiah was available first to the Jew, but also to the Gentile (Greek). Although this statement refers to the chronological spread of the gospel, it also refers to Paul's habit of bringing the gospel first to the Jewish synagogues before attempting to convert Gentiles. This also likely refers to the nature of the gospel, that it is a Jewish message. It concerns the Word of God given to the Jews in the form of the Old Testament (there was no New Testament at the time) and how the Kingdom of God is called Israel. At the same time, this very Jewish message was to be given to the Gentiles as well, who were to be grafted into the Kingdom of God.
The idea that Jews and Gentiles would both participate in the Kingdom of God was unheard of during the days of Paul. Up to that time, the only way to be a part of the Kingdom would have been to basically become a Jew by a conversion process. (However, this was not how Ruth, Rahab, Caleb, or the mixed multitude at the time of the Exodus, came into the Kingdom. This conversion process was a man-made process not initiated by God.) But God had intended that His Kingdom would be filled with both Jews and Gentiles. Paul championed the full inclusion of the Gentiles without a conversion process and many of the Jewish believers tried to reject this. The Council of Jerusalem upheld Paul's methods (See "The Jerusalem Council Decides")
In verse 17 Paul expressed that it was through the inclusion of both Jews and Gentiles that the righteousness of God was revealed. Salvation has always come through grace through faith. Paul then quoted Habbakuk as proof.
Habakkuk 2:4 (KJV)
Behold, his soul which is lifted up is not upright in him: but the just shall live by his faith.
However, faith is never separated from works. We become righteous by faith. We can't earn salvation by our works. But after faith we are to live righteously, and that is done by doing good works. Paul's statement of the just living by faith includes both ideas of righteousness, the righteousness we receive from God as well as the righteousness that we are to do on our own.
As Gentiles came into belief, the Jews, as a group, became a minority. Christianity became a Gentile religion and is now totally unrecognizable to the Jews. In fact, for the Jews to become a part of the Christian church, they must leave their identity behind, their Biblical feasts, kosher way of eating, and much more. They must participate in pagan holidays and renounce the admonition to never follow a prophet who draws them away from the Torah.
Deuteronomy 13:3-4 (KJV)
Thou shalt not hearken unto the words of that prophet, or that dreamer of dreams: for the LORD your God proveth you, to know whether ye love the LORD your God with all your heart and with all your soul.
Ye shall walk after the LORD your God, and fear him, and keep his commandments, and obey his voice, and ye shall serve him, and cleave unto him.
We Gentiles were not the "first." Yet, we have turned the tables and have now placed our Jewish brothers and sisters in the same position that we were in during the days of Paul. What happened to our Jewish message? It's time to put our house in order and to remember Paul's theme. Both Jews and Gentiles were to be in the Kingdom of God. Why have we built up a wall between us? Why have we changed into a new religion?