“Yet the law is not of faith, but ‘the man who does them shall live by them'” (Galatians 3:12).
Unlike some portions of Scripture that may be challenging to interpret, Paul the Apostle’s argument here in Galatians 3:11-12 is straightforward and easy to grasp. First, Paul quoted the Old Testament prophet Habakkuk in reminding the Galatian churches of an important Biblical truth: “…the just shall live by faith” (Galatians 3:11).
However, a person who follows a set of rules and regulations in an effort to find acceptance with God is not someone who walks by faith. Instead, he or she is focused on adhering to a set of standards- and it takes very little faith to follow a set of rules. But this leads us to another issue: no one can live up to God’s standards with 100% accuracy.
So when Paul says, “It is through obeying the law that a person has life” (NLT), he is stating a Biblical truth but one that is realistically impossible to achieve. Once source ties these concepts together with the following observation…
“Law and faith are mutually exclusive. The basic principle of the Law is found in Lev_18:5: The man who does these things will live by them. Only perfect performance could win divine approval under the Law, but since that was not achievable the Law could only condemn a person (cf. Jas_2:10) and cause him to cast himself on God in faith.” (1)
Another commentator carries this idea to its ultimate conclusion: “Only Christ could fulfill all the law (Matthew 5:17), so it is imperative that we receive His righteousness by imputation, and this can only be received through faith.” (2)
Finally, Paul offered a summary statement on the relationship between faith and the Law in the Biblical book of Romans…
“Moses said that a person could become acceptable to God by obeying the Law. He did this when he wrote, ‘If you want to live, you must do all that the Law commands.’ But people whose faith makes them acceptable to God will never ask, ‘Who will go up to heaven to bring Christ down?’ Neither will they ask, ‘Who will go down into the world of the dead to raise him to life?’
All who are acceptable because of their faith simply say, ‘The message is as near as your mouth or your heart.’ And this is the same message we preach about faith. So you will be saved, if you honestly say, ‘Jesus is Lord,’ and if you believe with all your heart that God raised him from death” (Romans 10:5-9 CEV).
(1) John F. Walvoord and Roy B. Zuck, Bible Knowledge Commentary [p.598]
(2) Institute for Creation Research, New Defender’s Study Bible Notes Galatians 1:19 https://www.icr.org/bible/Gal/3/12