In connexion with Romans 2:13, it becomes clear that Galatians 2;21 cannot refer to the Moral Law.
In Galatians 5:4, Paul directly addresses those who seek justification for the forgiveness of sins through adherence to the ceremonial law rather than through faith in Christ:
You who are trying to be justified by the law have been alienated from Christ; you have fallen away from grace.
Here, Paul makes it clear that justification in this context means receiving forgiveness of sins and being made right before God. He warns that those who seek this justification through obedience to the Mosaic ceremonial law such as circumcision, temple sacrifices, or purification rituals are
rejecting the grace of Christ. Instead of trusting in the atonement of Jesus, they attempt to earn forgiveness through their own religious works, which Paul calls a departure from grace.
Similarly, in Romans 10:3, Paul rebukes those who reject God’s way of granting forgiveness and righteousness and instead try to achieve it through their own efforts:
For they being ignorant of God’s righteousness, and seeking to establish their own righteousness, have not submitted to the righteousness of God.
Here, “God’s righteousness” refers to His way of granting
justification the complete forgiveness of sins through faith in Christ. But instead of accepting God’s way, some try to establish their own righteousness through religious observance, thinking that their works such as following
Jewish sacrifices, dietary laws, and ritual purity will secure
their justification.
Thus, in both verses, justification is clearly about the forgiveness of sins and being made right before God. Paul strongly emphasizes that this forgiveness is not obtained by personal effort, obedience to the Law, or religious rituals, but
solely through faith in Jesus Christ.
This may also include the Moral Law for those who seek justification for the forgiveness of their sins by obeying it, which Paul exposes as a false way of obtaining righteousness.
We do not deny that. However the Moral Law remains essential for final salvation as a directive and instructive way for the standard of righteousness
Romans 2:13 For not the hearers of the law are just before God, but the doers of the law shall be justified.
John 15:14 You are my friends if you do what I command you.
Faithfulness to God’s Law and Faith are closely linked.
James 2:23 And the scripture was fulfilled which saith, Abraham believed God, and it was counted unto him for righteousness: and he was called the
friend of God.