James Anderson has written a short blog post after reading VanDrunen’s “A Biblical Case for Natural Law” and “Living in God’s Two Kingdoms”. He does a good job of showing how Natural Law 2K is internally inconsistent.
Yet there is an even greater oddity here. VanDrunen’s 2K doctrine not only implies that he should oppose the display of the the Decalogue on a courthouse wall; it also implies that he could not oppose it as a point of public policy. Why? Simply because his 2K doctrine is based on the teachings of Scripture and not on natural law. (At any rate, VanDrunen makes his case for 2K doctrine from Scripture — it leans heavily on covenant theology — and it’s hard to see how one could make such a case apart from Scripture.) Since “politics is a matter of the common kingdom” (Living in God’s Two Kingdoms, p. 194) and the common kingdom is ruled by natural law alone, any point of public policy based on 2K doctrine cannot be defended in the civil sphere as a point of public policy. This strikes me as very odd.
http://proginosko.wordpress.com/2011/02/09/two-kingdoms-ten-commandments-one-objection/