This is the approach to Scripture taken by Calvin, Knox, and the Westminster Assembly (1643-47), according to M. G. Kline. The Theonomic thesis is defended by Greg Bahnsen, who argues for a basic continuity between the Old and New Testaments, and advocates the abiding validity of the OT law “in exhaustive detail” (though recognizing the ceremonial and temporary character of Levitical and temple-related ordinances).
In one sense, the debate over Theonomy is misleading. Its proponents claim that all Old Testament laws are binding unless repudiated by the New Testament. Opponents claim that the New Testament repudiates most of the Old Testament, which itself is a Theonomic claim. Both sides believe that the New Testament controls our use of the Old, but differ as to what the New Testament says about many Old Testament commandments.
It turns out that Theonomy is a heuristic approach, but not a hermeneutical one. Theonomy is also a predilection toward political and social issues which opponents of Theonomy do not share. Advocates of Theonomy claim that opponents are infected with “neo-platonism,” which tends to place low emphasis on politics and other social questions. Those who are vitally interested in such “this worldly” subjects are more likely to seek and find God’s will in the Old Testament than those whose concerns are more “spiritual.”
According to the Theonomic perspective, Socialism is not just inefficient, it is immoral. Nevertheless, most adherents of the Theonomic view are unwilling to condemn all socialism. Thus, although the basic Theonomic thesis is presupposed in our defense of anarcho-capitalism, it should be noted that anarcho-capitalism is hotly disputed by nearly all advocates of the Theonomic thesis.
Section VII (out of X) in Bahnsen’s book is entitled “Application of the [Theonomic] Thesis to the State.” Most people mistakenly assume that this particular application of the Theonomic thesis to the State by Bahnsen is itself the Theonomic Thesis. The political views of the “Christian Reconstructionists” constitute only one possible “Application of the Thesis to the State.”
Definition of “Sin”
Our thesis (stated more clearly in Tab 10) is that the formation and maintenance of the State is sinful. Our definition of “sin” is a Theonomic one.
Q14: What is sin?
A14: Sin is any [lack] of conformity unto, or transgression of, the law of God. (Westminster Shorter Catechism)
Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law. (1 John 3:4)
The French pamphleteer Frédéric Bastiat, in his short but influential book The Law (1850), wrote:
See if [the State] takes from some persons what belongs to them, and gives it to other persons to whom it does not belong. See if [the State] benefits one citizen at the expense of another by doing what the citizen himself cannot do without committing a crime.
“The State” is in fact the self-conscious institutionalization of activities which cannot be done by moral private citizens. The distinction between "the State" and private persons is the alleged morality of State actions which would otherwise be roundly condemned as immoral if perpetrated by private parties.
Our thesis is that Scripture provides no justification for these otherwise-sinful acts.
 Kline, M.G., “Comments on an Old-New Error,” Westminster Theological Journal, vol. XLI, No.1 (Fall 1978).
 Bahnsen, Greg L., Theonomy in Christian Ethics, Nutley, NJ: The Craig Press, 1977.
 See the explicitly non-Theonomic views of former Theonomist James B. Jordan: http://www.biblicalhorizons.com/biblicalhorizons/mBH.shtml?bh/BH001.htm