I've heard this only talking to Jews teaching.Christians hellenize the Scripture to their own wounding.
Paul was addressing the "Jews" first and then the Greek/Gentile believers.
The 'just shall live by faith' in the beginning of his epistle is a "Jewish" Scripture addressed towards the "Jewish" believers. The Gentiles know nothing of the Law, the Psalms, and the Prophets.
Everything Biblical and Scriptural is to the "Jew" first for this is who Messiah came to as was Promised by Moses. Christ came to the lost sheep of the house of Israel, not the Gentile.
It is all encapsulated in this key verse.
Notice who is first.
8 But unto them that are contentious, and do not obey the truth, but obey unrighteousness, indignation and wrath, 9 Tribulation and anguish, upon every soul of man that doeth evil, of the Jew first, and also of the Gentile; 10 But glory, honour, and peace, to every man that worketh good, to the Jew first, and also to the Gentile: Rom. 2:7–10.
The Revelation has a "Jewish" flavor. God is warning His Chosen people Israel of the times to come in which they will endure great trial and anguish. The Lord's prayer is a "Jewish" prayer Christ has beforehand prepared for His people Israel.
There are many gospels/good news in Scripture.
Paul quotes the Old Testament Scriptures to the "Jewish" believers at Rome who know the Old Testament Scriptures.
Apply them to the "Jew" first, and when you have the original meaning then apply them to the Gentile believer.
But there were Christians before the cross that believed in Christ.
In Hebrew He was called Messiah.
To the "Jew" FIRST and then the Gentiles for the "Jews" came FIRST.
I'm not going to put away much of the Bible, and give God's words no heed, just because I'm not a born Jew in the flesh.
The eternal rule, principles, and oracles of God are for any man to hear and obey, beginning with Adam.
The only things Jesus the Jew taught, that do not apply to all men today, is that of the law of Moses pertaining only to them under the OT made at Sinai and in the wilderness.
This teaching of Jesus only speaking to natural Jews, as well as prophecy of the NT, is just more carnal Jewish pride on parade.
Someone wants to tell me that the meek shall inherit the earth does not apply to me by faith in Jesus, I just ignore them. Dittoes with be ye perfect as your Father in heaven is perfect. Dittoes with them that are blessed by reading, hearing, and keeping the things of prophecy written therein.