Geoffrey B Wilson's digest of Reformed commentary on the NT epistles (Banner of Truth) to my mind consistently distilled significant material, often in quotes, I never found too difficult. The books were once all individual copies, now bound together in two vols.
https://banneroftruth.org/us/store/theauthor/wilson-geoffrey/
My other thoughts, re. "the law is not of faith," Gal.3:12.
Galatians is a letter about justification; at least, Paul makes the issues facing the Galatian church to be seen truly as nothing less than beginning with the gospel on the right first-step. Or else it is a false gospel and false salvation. These words of Paul are not to be read apart from the context. "Law" and "faith" are not abstract, self-contained expressions with Platonic meaning expressed in covenant-concrete ideals. They are not matter and anti-matter, as if this phrase of Paul's effectively pitted all things legal against all things believable.
But the question is (just look at the context, v11) is "how is a man justified in the sight of God?" In which case the answer is either-or, either law or faith but not both; and frankly never by law, not in the past and not in the present. This is proved by Abraham, whose justification antedates the law and even the institution of circumcision (properly Abrahamic and not Mosaic). So, whatever Moses' law and covenant is expected to do (being given 430yrs later), it is not the true solution to the problem of how sinners may be justified. It isn't an "improvement" on the covenant of
promise which was ordained to Abraham and his children (who are his seed by sharing in his faith, regardless of their natural origin).
It is NOT the case that true Christian Faith is antinomian, having nothing to do with law. The law is "holy, just, and good." The law is distilled (not evaporated away) into "love." Love is certainly no antithesis to faith. Sin is contrary to faith, and sin is lawlessness. Divine law exists to arrest and condemn the lawless and to oppose everything that is "contrary to sound doctrine." So, in NT terms, law ends up on the
right side of our religion, not on the flip-side. The law is a revealer of truth, a beacon to draw to safety and to warn from danger, a light to one's path.
The days of Israel-under-the-law did not proclaim (legitimately) any alternative use of the law. But it certainly DID show with abundant clarity how crushed and condemned sinners were who were laid under its yoke. The
hugely emphasized lesson of the Mosaic administration in
abundant illustration: it is impossible to escape legal condemnation. Paul does not teach a "New Covenant" legal treatment that confounds the former "Old Covenant" endeavor. To think of that law thusly in any generation was to mistake it, from its inception. "The law is not of faith" was as true for the OT Israelite Faith as it is for the Christian Faith, both having one and the same Object. Honestly, the Mosaic covenant proves--just as much as Abraham's or Christ's covenant--that justification must be by faith, or it will not be found.
There is
no justification for sinners in or by the law, but only by faith. ALWAYS it was by faith, even in Moses' day. On this question of divine acceptation, law and faith are poles apart.