From the early 4th century, when Christianity was declared a legal religion and properties were returned to Christians and persecution of Christians was forbidden, the Christian church gradually become intertwined with the empire. Gradually, paganism was marginalized and then eventually made illegal. Emperors in the 4th century and following intervened directly in the life and assemblies of the church. The emperor convened the Council of Nicea in 325. In 380 the empire sided with Nicene orthodoxy and declared its opponents to be heretics. In the East and in the West Christianity gradually became the de facto state religion. As with developments in worship, the 4th century was decisive for future patterns in the way that the church would relate to the broader culture. The church enjoyed more than 1,400 years of favored status. In the 16th and 17th centuries, during the Reformation and post-Reformation periods, the debate between Rome and Protestants was not whether there is a true church that should be enforced by the state but which one it should be. Protestant resistance theorists asserted both a distinction between the church and the state and treated the emperor as if he were a new King David and, e.g., France as if it were a new Israel. The Scots Presbyterians did arguably the same thing in their national covenants.
In the West, the privilege enjoyed by the visible church began to be dislodged by the various Enlightenment movements that would come to dominate the academy and cultural elites for roughly the next 250 years. Still, as a practical matter, Christians continued to experience favored status until, in historical terms, very recently. In the West it has only been since World War II and practically since the 1960s that the Christians have really noticed any profound change. In the 1960s, in the USA, school-sponsored prayers were declared unconstitutional. In the 1970s and 80s the so-called “Blue Laws” began to be overturned (they still exist in some places), marking the beginning of the end of the state-sponsored recognition of Sunday as the Christian Lord’s Day or Sabbath. Remember that though the American constitution forbids any federal church state-sponsored churches continued to exist well into the 19th century.
One result of this long heritage of entanglement between church and state is that many Christians still default to what has been called the Constantinian model. They want the state to act like the church, when it suits them. One sees this on the Christian right and on the Christian left. A Republican Presidential candidate is proposing a new federal agency to promote Judeo-Christian values. He has also argued that in view of the future judgment, Christians should support his vision of a social-welfare safety net. The Christian right wants the state to enforce personal morality more aggressively (e.g., the Moral Majority). The Christian left wants the state to act redemptively in a corporate capacity. The state-Messianism of the Christian left manifests itself in the grounds given by the Christian left for their policy that the USA should receive and resettle large numbers of Syrian refugees.
Repeatedly advocates of the policy of Syrian resettlement in the USA invoke the Old Testament laws protecting the sojourner. E.g., Deuteronomy 10:19 “Love the sojourner, therefore, for you were sojourners in the land of Egypt” (ESV). They invoke some of the 613 commandments, which Jews and Christians confess that God gave to Israel, and apply them directly to the USA without so much as a “by your leave.” Every theocrat, theonomist, and Christian Reconstructionist says amen to this use of Scripture. One suspects, however, that the Christian leftist would not be pleased to see the state enforcing Biblical religion at the point of the sword. It would awkward to to admit thousands of Syrian refugees only to prosecute the Muslims majority for denying Biblical religion. We may be sure that the Christian leftist would be quite opposed to the state-enforcement of Mosaic sexual practice. They want an enlightened, selective theocracy.
There is an alternative. Even as they sought to reform the state church in England and Scotland, the Westminster Divines confessed a very important and truly helpful distinction in the way that Christians understand the Mosaic law after the cross:
1. God gave to Adam a law, as a covenant of works, by which he bound him and all his posterity to personal, entire, exact, and perpetual obedience, promised life upon the fulfilling, and threatened death upon the breach of it, and endued him with power and ability to keep it.
2. This law, after his fall, continued to be a perfect rule of righteousness; and, as such, was delivered by God upon Mount Sinai, in ten commandments, and written in two tables: the first four commandments containing our duty towards God; and the other six, our duty to man.
3. Beside this law, commonly called moral, God was pleased to give to the people of Israel, as a church under age, ceremonial laws, containing several typical ordinances, partly of worship, prefiguring Christ, his graces, actions, sufferings, and benefits; and partly, holding forth divers instructions of moral duties. All which ceremonial laws are now abrogated, under the new testament.
4. To them also, as a body politic, he gave sundry judicial laws, which expired together with the State of that people; not obliging any other now, further than the general equity thereof may require.
5. The moral law doth forever bind all, as well justified persons as others, to the obedience thereof; and that, not only in regard of the matter contained in it, but also in respect of the authority of God the Creator, who gave it. Neither doth Christ, in the gospel, any way dissolve, but much strengthen this obligation.
The law that God gave to Adam in creation, the covenant of works, was re-stated to Israel in the Ten Commandments. That law we recognize as an expression of God’s universal moral will. It was also frequently called by Christians “the natural law” (lex naturalis or lex naturae). They distinguished between two tables of the law, the first table referring to man’s duty to God and the second to man’s duty to man. The divines confessed two other distinctions. They distinguished between the Israelite ceremonial laws concerning strictly religious (cultic) matters (e.g., washing, purification, sacrifices etc) and the civil laws. Those were fulfilled by Christ. The civil or judicial laws, they confessed, “expired” with the Israelite state. All that is left is the “general equity” of them, which we see reflected in Paul’s instruction to Christians to submit to the pagan magistrate Nero (Rom 13). Nowhere in the New Testament does one find even the slightest whisper of a hint that the apostles sought state sanction or much less imposition of Christianity upon the Roman empire. Indeed, after the apostles, the Epistle to Diognetus (ch. 5), Irenaeus, Justin, and Tertullian did not ask for state-sanction of Christianity. They only asked to be left alone.
Nevertheless, under the influence of the Constantinian settlement, virtually everyone in the Christian East and West was theocratic in their understanding of the law thus they sought to enforce the first table by the use of the sword. After the end of the Thirty Years War in 1648, however, Christians began to raise questions about the theocratic approach, the state-enforcement of the first table. In the American experiment, citizens agreed not to have a state-enforced religion (at least at the federal level) but they did so in within the broader Constantinian context. We are still learning how to work out the consequences of distinguishing church and state, of learning how to look at the state as a secular institution, i.e., as an institution that has no role in enforcing a favored religion.
One consequence of a secular state (as characterized above; please note that I did not write “secularist“) is that just as it is improper for theocrats on the Christian right to seek to use the levers of civil authority to impose their vision of the future (eschatology) so too it is improper for theocrats on the Christian left to use the power of the state to impose their vision of the future upon society. Both of them are, in my opinion, different versions of the Anabaptist desire for an earthly golden age, which the Swiss Reformed Churches rejected in the Second Helvetic Confession (ch. 11) in 1566:
We further condemn Jewish dreams that there will be a golden age on earth before the Day of Judgment, and that the pious, having subdued all their godless enemies, will possess all the kingdoms of the earth.
Rather than ping-ponging between the theocracies of the the Christian Left and Right, we should recognize that we live as Calvin wrote, in a “twofold kingdom” (duplex regimen). Surely we understand what that means differently from the way he did but it is a good and helpful distinction. It means that we have duties to both the civil magistrate and to the church. As members of the civil polity, which is best understood as a covenant of works, we ought to advocate policies that are for the welfare of all citizens. Those policies are are best grounded in natural revelation, accessible to all who will use their senses and rational faculties. As members of the spiritual polity (represented by the visible church), which is a covenant of grace, Christians have a duty to show love and grace to those the civil magistrate admits to the protections of the republic. The United States is not a new incarnation of national Israel nor is it the church. It is a civil polity. As such it does things that the church cannot and should not do (e.g., bear the sword). The church is the Israel of God, in Christ. The church does what the state cannot do, namely show grace to the undeserving and to administer the keys of the eternal, spiritual kingdom.
It is not easy to know how to relate our duties to both realms simultaneously and faithful Christians will disagree but we have liberty to do so. One may think that it is good civil policy to admit Syrian refugees and another may think it foolish to admit thousands of refugees. Now we are having the sort of discussion we should: the proper application of wisdom and natural law to civil policy rather than a debate about who is or is not a faithful Christian using the machinery of the state to enforce their eschatology upon citizens who may or may not agree with them.