Romans 3:27 meaning

If Paul is anything, he is persistent. Here again, he makes the same point he has already made many times (and will continue to make): Then what becomes of our boasting? It is excluded. By what kind of law? By a law of works? No, but by the law of faith (v 27).

There is no possibility for us to participate in being justified before God by keeping the law. None. Zero. Why? Because we cannot keep the law. Every one of us is under sin (v 23). Paul includes himself as a sinner, saying he is no better than the hypocritical slanderers (v 9).

Further, there is no boasting for our participation in being justified before God because Jesus alone is the justifier (vv 26-27). The justifying before God that Jesus does is completely apart from the law (v 21) and is given completely freely, with no strings attached. That gift is received by faith alone (vv 24-25).

The competing Jewish "authorities" opposing Paul and his co-ministers Priscilla and Aquila (Romans 16:3-5) maintain that adherence to the law is necessary to be justified before God and have slandered Paul's insistence that our justification before God is separate from the law, by grace, received by faith. Paul, here, is continually and artfully deconstructing the slander that would undermine his gospel message if it were to be adopted by the world-famous believers in Rome (Romans 3:8).

The law of works, which includes circumcision, is of no consequence in being justified in God's sight, therefore there is not basis for boasting in our religiosity. In chapter 2, Paul noted that his opponents "rest on the law and make your boast in God" because of their knowledge and adherence to Jewish religious rules (Romans 2:17-21). However, such rule-following does not change the heart, it just leads to an elevated capacity for rationalization.

What trumps the law of works is the law of faith. The law of faith is what justifies us before God, as Paul will explain next. It is also what sanctifies us when we walk in faith in our daily lives. As Paul says in chapter 8:

"so that the requirement of the Law might be fulfilled in us, who do not walk according to the flesh but according to the Spirit."
(Romans 8:4)

Thus Paul continues with the theme from chapter 1, that righteousness (harmony with God's good design) comes about through faith, from the start to the finish. Righteousness begins when we are justified before God through faith (John 3:14-15, Romans 4:1-3). Then we experience the fruits of righteousness when we walk in faith, believing that God's ways are for our best.