Theonomy, from theos (god) and nomos (law), is the idea that God's Law-Word, including the judicial laws of the Old Testament, should be observed by modern societies. This idea is not to be confused with the idea of "theonomous ethics" proposed by Paul Tillich.
Various theonomic authors have stated such goals as "the universal development of Biblical theocratic republics", exclusion of non-Christians from voting and citizenship, and the application of Biblical law by the state. Under such a system of Biblical law, homosexual acts, adultery, witchcraft, and blasphemy would be punishable by death. Propagation of idolatry or "false religions" would be illegal and could also be punished by the death penalty. More recent theonomic writers such as Joel McDurmon, President of American Vision, have moved away from this position, stating that these death penalties are no longer binding in the new covenant. Polemicist and Theonomy critic, JD Hall, who debated McDurmon in 2015, has argued that abandoning Mosaic penologies such as the death penalty means that McDurmon and others who hold similar positions cannot be said to hold to theonomy in any meaningful way.
According to theonomist Greg Bahnsen, the laws of God are the standard which Christian voters and officials ought to pursue. Civil officials are also not constrained to literally enforce every Biblical law, such as one-time localized imperatives, certain administrative details, typological foreshadows, or those against envy and unbelief. "Rulers should enforce only those laws for which God revealed social sanctions to be imposed".
In the terminology of Christian Reconstructionism, theonomy is the idea that, in the Bible, God provides the basis of both personal and social ethics. In that context, the term is always used in antithesis to autonomy, which is the idea that the Self provides the basis of ethics. Theonomic ethics asserts that the Bible has been given as the abiding standard for all human government-individual, family, church, and civil-and that Biblical Law must be incorporated into a Christian theory of Biblical ethics.
Theonomic ethics, to put it simply, represents a commitment to the necessity, sufficiency, and unity of Scripture. For an adequate and genuinely Christian ethic, we must have God's word, only God's word, and all of God's word. Nearly every critic of theonomic ethics will be found denying, in some way, one or more of these premises.
Critics see theonomy as a significant form of Dominion theology, which they define as a type of theocracy. Theonomy posits that the Biblical Law is applicable to civil law, and theonomists propose Biblical law as the standard by which the laws of nations may be measured, and to which they ought to be conformed.
Some in the modern Reformed churches are critical of any relationship between the historical Reformed faith and theonomy, while other Calvinists affirm that Theonomy is consistent with historic Reformed confessions.