Jarvis Williams' commentary on Galatians is a commentary of one of Paul's most rhetorically charged and polemically sharp letters. Williams writes a commentary of the letter, not a commentary of commentaries. He grounds the letter in grammatical-historical exegesis, seeking to help readers understand Paul's Greco-Roman and Second Temple Jewish context of the letter. Additionally, the book seeks to move from exegesis to application in a few places in the commentary. The strength of the commentary is that it offers a lucid and concise exegesis grounded in Paul's first century context and applicable for twenty-first century readers.
In his New Covenant Commentary, Williams likewise stayed the standard framework: "south Galatia," middle date. He did well at bringing in the appropriate points of connection with the greater Greco-Roman and Second Temple Jewish worlds of Paul and the Galatians. He spent considerable time with some passages but only briefly covers many others.
Williams especially found himself in quite the predicament in attempting to uphold the traditional Catholic/Orthodox/Anglican/Protestant desire to consider many aspects of the Old Testament as providing authority for modern Christian faith and practice in light of how Paul was adamantly resisting such a position. His aside on the issue did not exactly persuade or convince.
Overall, however, a good and robust exploration of Galatians.