(I write this out of extreme respect for Dr R. Clark.)
Both theonomists and critics of theonomy share the same assumptions on “Constantinian.” For some reason theonomists (and many right-wing Reformed) want a “Constantinian” society, while common-grace amillennialists point out the evils of religious persecution. But why should Covenanting Reformed want a Constantinian society? It sounds a lot like a supra-national religious commonwealth. Like Roman Catholicism or the Holy Roman Empire, historic enemies of Protestantism. Does this mean I accept the common-grace alternative? No. Neither side really understands the term “Constantinian.” Ironically, the people who cavail against Constantinian don’t realize they are using the same arguments as today’s hippie Anabaptists.
The heart of the matter concerns whether the civil magistrate has the right to use the sword to protect the true religion. Dr Clark points to the ironic case of Guido de Bres, who authored Article 36 of the Belgic Confession, yet was martyred by Roman Catholic political authorities. Perhaps it is ironic, but we’ve missed something in the argument: is Guido’s position normatively true or not, regardless of current situations? For example, adultery and sodomy are wrong, yet they will not be punished by the American magistrate? Should I alter my theology to accommodate pagan political ethics?
We also see the common question, “The Apostles didn’t do x.” It is amazing how often Reformed folks default to a quasi-dispensational hermeneutics on political ethics. There are several lines of response: 1) the aforementioned objection is a logical fallacy of arguing what we ought to do from the silence of what is the case (even better, it’s two logical fallacies in one). 2) More often than not, the Roman state bailed out the apostles against anti-Christ Jews, so why would the apostles attack Rome? 3) We do see the NT move in language to the kingship of Christ (and eventual transformation of laws); cf any passage on the Ascension; Rev. 1, 11:15
The truth of the matter, we don’t want a Constantinian society. We want a covenanted nation. The problem with a Constantinian society is the same problem with natural law international relations (and I can’t help but point out that historic advocates of natural law also believed in “Constantinianism”). When two nations or corporate bodies both use natural law reasoning and yet are at odds, who gets to adjudicate? The Romanists have an easy (and consistent) answer: The Pope! I maintain, by contrast, that a Covenanted nation better actually represents (by analogy) the New Testament teaching on the Church (as a mirror): covenanted nations do not rule other nations, yet each nation is bound to the Covenant with Christ as the Head. Likewise, one presbytery doesn’t rule another presbytery, but each synod has Christ as the head.