When Paul talks about not being justified by works, he’s primarily, and often specifically, referring to works of the law.
One of the main reasons Paul got beat up by Jews in the Book of Acts is over this stance. From Acts 13:39:
And by him [Jesus Christ] all that believe are justified from all things, from which ye could not be justified by the law of Moses.
Them’s fightin’ words for the Jewish people. Several verses later we’re told that the Jewish mob expelled Paul out of their coasts.
There’s a lot of talk by Paul about not being justified by deeds of the law.
Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
Therefore we conclude that a man is justified by faith without the deeds of the law.
Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith.
Why is Paul emphasizing that so much?
Primarily because the Jewish people, who have had the law for thousands of years, thought they were justified by doing the law.
Of course, the law was impossible to do, and their history shows they did a horrible job of doing the law. The destruction of Jerusalem and Israel were a result of their failure to keep the law.
Here’s the thing though: The law was never given to save anyone.
The law was part of the covenant God made with Israel to stay in their land. Some of the Jews in the Old Covenant were saved, but most were not.
Being saved had nothing to do with being in the covenant. If you were a Jew back then, you were in the Covenant and thus, under the law, whether you wanted to be or not.
A Jew in the Old Covenant did not choose to be under the law; they were by birth. The law was not given to save anyone; it was given as a covenant between God and Israel to stay in the land.
But all along God had established that justification was by promise and faith. A person of faith under the Old Covenant would endeavor to keep the law and do the sacrifices with a heart right with God.
Killing animals didn’t take away sin. But under the Old Covenant, a person of faith would do sacrifices. Their dead animals didn’t remove sin; their faith did.
Before the law people were justified by faith. Under the law people were justified by faith. After the law people were justified by faith.
For by grace are you saved through faith is the only way anyone has ever been saved. God preached the Gospel unto Abraham saying in thee shall all nations be blessed. It is the everlasting Gospel.
If the law could give life, then Christ is dead in vain. If the law could justify, then we don’t need the Gospel.
We have the Gospel, therefore, the law could not have justified.
No one has ever been justified by deeds of the law. The law did not, does not, and can not save.
I am repeating myself a lot because people miss this point. People also then extrapolate that since we aren’t justified by deeds of the law, therefore we don’t have to do anything except nod our head yes at Jesus and His Gospel.
That is not Paul’s point. Paul’s point is that no flesh is justified by deeds of the law. That’s his point. He has no other point on this subject. That is it.
No flesh is justified by deeds of the law.