v. 23 You that boast in the law, do you dishonor God by breaking the law?
It is a rhetorical question on two fronts. Yes, when we break the law we dishonor God. But also, we break the law.
Paul learned from his own experience that following the law to its letter is impossible. He tried. He failed. From this experience comes his two great insights.
First of all, there is either keeping the law or not keeping the law. There is no half-way, sort of or mostly. The law demands perfection.
Second of all, since we cannot possibly achieve perfection, something else must save us. That thing is, he came to believe, faith.
Does this mean that the law is good for nothing? No. Elsewhere Paul calls it our "disciplinarian," and we need a disciplinarian. But following it is not what justifies us, makes us worthy, in the eyes of God.
Only faith does that. As we continue to read through Romans we'll have more chance to reflect on this truth. For now, let us thank God for the gift of faith.