Lehi goes on to teach that law is a necessary pre-condition of human liberty, not only in the political sense, though that is argued in the Book of Mormon, as well, but in the deepest existential sense. Agency is the fundamental ground of the human condition, as Lehi explains it. This is a theological position that Milton occupies, also, as I've argued before in this space. But they get there by very different routes, and that has everything to do with the meanings of liberty and law.
If Christians are tempted to self-congratulate, then, when we encounter arguments like Smith's suggesting that faith-based ideas are an essential (if hidden) supplement to what would otherwise be a waterless jungle of political discourse—well, we ought to remember that it's something of a jungle in here, too. There are as many interpretations of Christian liberty as there are "interpretations" of that high A we'll all be singing next Monday morning in the land of the free and the home of the brave. My advice: open your throat, support with the diaphragm, and reach for the sky.