Just to be fair here is a defense of Van Drunen. I am not sure how good it is because I haven't had the time to peruse it yet. Content wise it really doesn't address as much material Kloosterman addresses but maybe it is revealing. Read the whole thing guys. I am only posting the conclusion because it is a bit lengthy.
VanDrunen in the Hands of an Anxious Kloosterman:: Westminster Seminary California
VanDrunen in the Hands of an Anxious Kloosterman Conclusion
To conclude, I raise for readers' consideration not only that natural law and the two kingdoms are historic Reformed doctrines, but that they are part of the warp and woof of the Reformed system of doctrine. In classic Reformed theology, distinctive Reformed doctrines such as the Sabbath and the covenant of works were articulated with explicit reference to natural law. In classic Reformed theology, Reformed doctrines such as the regulative principle of worship and even justification were expressed with intimate relation to the doctrine of the two kingdoms. Perhaps that sounds preposterous, but it is true, as I hope to explain in some detail in the future. Is it any coincidence that the past century—precisely the time period in which natural law and the two kingdoms have largely fallen into disuse in Reformed circles—has witnessed serious erosion in commitment to the Sabbath, the regulative principle of worship, the covenant of works, and justification in Reformed churches? Or, to add another wrinkle, is it a coincidence that in the past couple of generations so many Reformed people have been tempted to embrace the theonomic movement and the majority that has resisted has offered for the most part only tepid and insipid alternatives? I do not think that it is in any sense a coincidence.
To put it one more way: Has the century of Reformed distaste for natural law and the two kingdoms been a golden age for confessional Reformed Christianity? I doubt many readers of Ordained Servant would think so. Our contemporary denominations that seem most serious about historic, confessional Reformed Christianity are small splinters off much larger bodies that have gone in different directions. Confessional Reformed Christianity has truly become sideline rather than mainline. Are our Christian primary and secondary schools and colleges, so many of which proclaim the neo-Calvinist vision of transformation and worldview cultivation and dismiss the two kingdoms idea as "dualistic," stronger theologically and academically now than they were some generations ago? My interaction with the kind of people who read Ordained Servant leads me to guess that a great many of you would answer no (which is why a great number of you homeschool your own children).
I realize that natural law and the two kingdoms seem like novel and suspicious doctrines to many Reformed people today. But turning against these ideas, I am convinced, has been to the detriment of Reformed doctrine, piety, and life in the world. Resist the attempt to revive these doctrines if you must, but a "conversation" about them will not be productive, nor even very conversational, if it puts these doctrines in a misleading and pejorative light and caricatures their defenders before the conversation has really begun.
To clarify, the article by VanDrunen linked above is not a response to Klooserman's recent review of Natural Law and the Two Kingdoms. It is a 2007 article from Ordained Servant responding to a critique of A Biblical Case for Natural Law that was recently republished at Westminster Seminary California. Obviously these issues are related and Kloosterman's response to both books is similar, but those looking for a full response to the Christian Renewal review will not find it here.