A Theory of Legislation: A Christian Perspective
A prominent question in political theory has been to ask, “Who should rule in society”? Who should make the rules that govern us all? Who should legislate? For Plato, it was the philosopher; for Erasmus, the virtuous; for Machiavelli, the powerful; for Lenin, the proletarians with power secured for them by a vanguard party.
But before we can ask "who should rule in a society"?, we must establish why anyone has a right to rule at all. Unless you believe that “might makes right” there must be some ground for human authority. In a word, God.
God is the Ground of Legislative Authority
As Creator, God is the ground for all rules that bind men. He has made known His will through a moral law that is a reflection of His character. A part of the task of government is to make laws based on God’s moral laws. God’s moral laws come to us in the form of divine commands that bind us. Furthermore, God has given us an intuitive grasp of these commands as a part of the “law written in our hearts…” We often refer to this "law written in our hearts" as "conscience." This “law written in our hearts” is that set of divine commands that we find revealed in the Bible, commands that prohibit such acts as killing and stealing.
Governments are under these divine commands because God has both the power and the right to make rules that bind all men. He has the right in the sense that he is the Creator of all things. As an act of His sovereign right and power, God has delegated to government the authority to impose penalties on the violations of these divine commands. In western democratic nations, we have mostly delegated that function of lawmaking to the legislature.
What's Binding; What's Not
Many today, including many Christians, are confused about what aspects of the Bible are binding upon a society and what aspects are not. First, let’s deal with what is binding. God’s moral law is binding; this is not optional. Men are to pass laws that reflect God’s rules given in the form of commandments. Rules prohibiting theft, murder, sodomy, and kidnapping, for example, are not optional. Rulers must impose these sanctions on society; it is a moral obligation as God has stipulated that these are the rules that govern all men, wicked and righteous. It is the violation of these rules that defines a man as an “evil doer” and makes him subject to the revenging sword of the civil magistrate as spoken of in Romans 13.
But, not every rule or proclamation mentioned in the Bible is to be imposed by civil authority. The message of the gospel is not to be imposed. Doctrinal beliefs (such as the Trinity, belief in the Resurrection) are not to be imposed by the law. The state is to use the sword to punish wrong behavior, not wrong belief. God gives to the state and the church ways of dealing with offenders in their orbit of authority. The state bears the sword; the church, rebuke, and possible excommunication. The church is to make the distinction between the saved and the lost; the state makes the distinction between the lawful and the unlawful. Both church and state are under God, but each serves a different role.
Translation, Not Creation
God has given to men the authority to make laws that reflect His righteous character. However, strictly speaking, men do not make laws. Rather, they translate the law of God into their own society. As historian Paul Johnson notes,
The phrase 'a society under God and law' is appropriate because Parliament is not the primeval legislature. It does not, and cannot, create law from nothing. Rather it inherits, and interprets, a system of moralistic law, much of which is enshrined in the organic corpus of Common Law. Hence we might define the function of Parliament as making the necessary adjustments between the system of fundamental law and the changing needs of society. Its primary function is therefore as a revising body: it is a law-making body only in a secondary sense. It cannot make fundamental law. It cannot make marriage a crime, murder a duty, or falsehood meritorious. 
So legislatures are bound by a “fundamental law” but this law is not a law of their making. Today within democratic states, there is the idea that the legislature can make any law that it pleases so long as it’s done by lawful process and has the people’s approval. The foolish laws that we see coming from legislators and the waste of the people’s money comes from the hubris that there are no fixed standards of moral behavior. Far too many legislators believe that if they want to pass a law, and if they can get away with it, they are at liberty to do so regardless of whether or not that legislation violates fixed standards of morality. Sadly today, we have a group of legislators that think that they can spend money without regard to paying the bills. All the while, they continue to pile up the national debt as they mortgage away their children’s future as they curry more votes to themselves.
Now more than ever, we need a generation of men and women who understand God’s fundamental law and will insist that their rulers abide by God’s standards of righteousness. However, that will not be enough. The best way to change policy is to change the policymakers. Men and women of godly character that are aware of God’s fundamental law will need to run for office and reverse the irresponsible policies of our current governments.
Political Philosopher Jay Budziszewski Discusses Natural Law
In summary, laws must conform to a moral standard, a standard that is set by God. As President Calvin Coolidge put it: “Men do not make laws. They do but discover them. Laws must be justified by something more than the will of the majority. They must rest on the eternal foundations of righteousness.” These “eternal foundations of righteousness” have been imparted to man by their Creator in the form of a moral law, a law that man is intuitively aware of. As political theorist Jay Budziszewski puts it, it is a law that man "cannot not know." The early view was that man did not actually make laws, but rather he discovered them. As public administration scholar, Richard Stillman put it:
Our Tudor institutional heritage saw law as divinely inspired, not man-made. It was ‘discovered,’ not humanly created: unchanging, not changeable. This was a characteristic medieval idea of all authority as deriving from law.’ In short, the idea of fundamental law was based on a premodern concept—namely that the law makes the king, not the reverse. 
Legislative authority, then, is grounded in an eternal law, not upon the power of the strongman or the “will of the people.” It is incumbent upon the people of free nations to choose representatives that will act wisely, that will treat their time in office as a public trust and make laws that are grounded on the “eternal foundations of righteousness.”
 Paul Johnson, The Recovery of Freedom (London: Blackwell, 1980), 179.
 Richard J. Stillman II, Preface to Public Administration: A Search for Themes and Direction (New York: St. Martin’s Press, 1991), 25.