What does Romans 3:19 mean?
Paul sums up his case that the law cannot protect anyone from God's judgment of their own, personal sinfulness. Anyone who believes that is deceiving themselves. Paul writes that the law speaks to those under the law. And what does it say? It says, "You can't keep the law." This was the conclusion supported by Paul's prior references to the Old Testament: that nobody lives a life of "righteousness" in comparison to the standards of God.In other words, Moses' law, God's gift to Israel, does not provide any protection from God's eternal judgment for human sin. Not for Jews, nor for Gentiles. Instead, the law reveals just how much we humans sin. It forces us to agree with God that we deserve His anger because we now understand all of the ways in which we have sinned against Him.
In this way, Paul writes, it shuts every mouth. Put another way, the law takes away all of our arguments and excuses that we are worthy of God's approval on our own merits. Clearly, the law shows us, we are not.
This is true for every individual in the "whole world," Paul declares. Both Jews and Gentiles will be held accountable to God. On our own, all of us would be found to be guilty, to be "under sin." Soon, though, Paul will show us the opportunity to be declared righteous before God through faith in Christ. He's not quite there yet, however.