St. Paul is talking about the MOSAIC LAW, regarding what can SAVE US. This topic is talking about CIVIL LAW, and how it's used for an ordered society. I'm not sure why you'd be confusing those two radically different things.
The end result is the same, because the principles at work are the same. You won’t live what’s not in your heart to live.
That’s why God said he would write his law in the hearts and minds of his people.