There is a very good chance that the 2008 Republican nominee for President will, for the first time in party history, not be a Protestant but rather a Roman Catholic or a Mormon. Historically, the Republican Party has been the party of America's Protestants, both Mainline and, more recently, evangelical. Not long ago, the idea of a Catholic winning the Republican nomination was unthinkable. This year, ironically, some Republican voters probably will support the Roman Catholic candidate (Rudy Giuliani) because they are even more uncomfortable with the notion of voting for a Mormon (Mitt Romney). Religion matters in American elections. There is simply no question that many American voters take a candidate's faith into consideration before they cast a ballot. The question at hand is whether they should.
 The familiar Lutheran distinction between the two kingdoms is useful here. God rules the right-hand spiritual kingdom through the gospel and grace and the left-hand secular kingdom through law and the sword. The spiritual kingdom is an internal kingdom existing within the hearts of Christians. It produces true righteousness. The earthly kingdom is an external kingdom that exists in the rest of the world. It does not produce righteousness but only peacefulness. Since the spiritual kingdom is a kingdom of faith, the earthy government, which effects only our external actions, has no authority there. And since the earthly kingdom is--according to Luther--largely a kingdom of unbelievers, the earthly prince should not try to rule it through the Gospel.
 Since rule in the earthly kingdom is not based on the Gospel, there is no reason why the earthly prince must necessarily be a Christian and consequently no reason why we, as voters, should make our support of candidates conditional upon their profession of Christian faith. We are not electing pastors or bishops; we are electing presidents and governors, and non-Christians can fill these offices as well as Christians.
 However, while Luther recognized that an earthly prince did not necessarily have to be a Christian, he also saw an advantage in the prince being a Christian. When the government wields the sword properly-which means solely for the purpose of restraining the wicked and protecting the good-it preserves peace on earth and is a great benefit to all, Christian and non-Christian alike. When the sword is used wrongly, to make the prince powerful or rich, everyone suffers. Unfortunately, the power for the sword proves a great temptation for most mortals. In On the Secular Authority, Luther wrote that most princes are of the latter kind, selfish and corrupt. Selfless princes are a "miracle… not impossible, but quite unusual."  According to Luther, the only hope of having a selfless prince is when the prince is a Christian who has the Holy Spirit within. A Christian prince will approach the office as an opportunity to serve others rather than as an opportunity for self-aggrandizement. Such righteous behavior can be expected of "No one but a real Christian and one who is full of the Spirit…. It cannot be done without grace."
 Many Christians today would reject Luther's suggestion that only a true Christian can be a good ruler. Even Luther would concede that official church membership tells us nothing about the true status of anyone's soul. Furthermore, we find many examples in history and in everyday life of non-Christians who demonstrate as much selflessness as most Christians we know. But Luther's point that an individual's faith will influence how that individual fulfills the duties of a public office remains valid. Though we recognize Luther's distinction between the right- and left-hand kingdoms, or Jefferson's concept of a "wall of separation" between church and state, our beliefs in public life and private faith cannot be neatly separated. Even in a liberal democratic society, public life involves debate over normative concepts such as justice and the dignity of human life. Our understandings of these concepts inevitably are influenced by our religious faith. It is true that, as-for example-former presidential candidate Senator John Kerry has argued, a Roman Catholic politician will not necessarily try to use the power of the state to enforce the Catholic Church's teaching on the sanctity of human life. However, many public officials will be confronted with policy issues such as abortion, the death penalty, and euthanasia, issues in which human lives are at stake. When deciding on these matters, public officials should draw their own conclusions about what is right and not simply defer to their faith's teachings, but their determination of right and wrong will be influenced by their faith. It is simply not possible for a sincere Catholic or Mennonite or Muslim or member of any other faith to decide these issues without recourse to faith, somehow to create a wall of separation between religion and politics within his or her own mind. A candidate's profession of a particular religious faith clearly then is a matter of legitimate interest to voters, at least to the extent that the faith is sincere and is somehow relevant to a policy issue of interest to voters.
 Some might argue that even if the above is true, voters who are worried about a particular candidate's religion usually are not adequately informed to draw conclusions about how that religion's teachings are relevant to matters of public policy. Their vote against a Catholic or a Mormon or a Jew will be based not on knowledge of these faiths, but on ignorance. In short, they will vote out of religious bigotry.
 It is true that some voters are influenced by religious bigotry, just like some voters are influenced by racism and sexism. But it is not true that every voter who considers religion when voting, even if that voter's knowledge of a religion's teachings is incomplete, is acting out of bigotry or some other unethical motive. Most voters-at least those with any level of public awareness-possess some general knowledge of the political positions associated with various faiths. It is fair to assume that those who are themselves regular attendees at a church or other place of worship will have gained some sense of the political positions supported by leaders of their own faith. If they pay a minimal amount of attention to current events, they may know that evangelical Christians are usually opposed to abortion and gay marriage and that Roman Catholics also are usually opposed to the death penalty. Not every voter will possess this kind of information, but many will, and most will have at least some information about connections between faith and public policy.
 All of these pieces of information can serve as what political scientist Samuel Popkin calls "information shortcuts."  An information shortcut is a fast and efficient, if not completely reliable means, of gathering information. Voters know that to cast an informed vote, they must have information. However, most voters are regular people with busy lives who do not have a lot of time to spend gathering political information. So they do the rational thing, they take shortcuts. For example, it can be difficult to find out exactly what a candidate thinks about abortion, but it is fairly easy to find out if a candidate is a Republican or a Democrat. Since more voters already know the two parties' position on abortion, they will assume that Republican candidates will think like Republicans and Democratic candidates like Democrats. This is certainly not a foolproof decision making process, since some Republicans support abortion rights and some Democrats oppose them. However, for voters who lack complete information and the time to gather it, this is a rational way to decide how they should vote. Although not perfect, it does not seem to be unethical.
 Political party membership is one kind of information shortcut. It works particularly well during general elections when there typically are only two major candidates, each representing a clearly identified and well known political party. But during primary elections, voters often have to decide between three or four or more candidates who all belong to the same party. When this happens, voters will look for other shortcuts, and religious affiliation can serve this purpose. Voters can cast a vote for or against a candidate based on their knowledge that a candidate adheres to a particular faith and their existing knowledge of the values and political positions associated with that faith.
 This is not a perfect way to decide how to vote. It assumes that what a voter knows about a candidate's religious affiliation and about the values associated with a faith are accurate. And even if the voters' information is correct on both counts, their decision might still be wrong. A voter might know that a candidate is a Catholic and that the Catholic Church opposes abortion and thus assume the candidate also opposes abortion, and this assumption could well be wrong. But the use of religious affiliation as an information shortcut does not seem any more suspect than the use of party labels or other short cuts such as sex, ethnicity, or social class.
 In sum, voters act appropriately when they evaluate candidates for public office based on anything that is relevant to how that candidate will perform the office. A candidate's religious faith is directly relevant to the performance of public offices, not simply in terms of the ethical standard which that candidate will bring to the office but also in terms of what this candidates thinks about important political issues of this day. Therefore, voters, the media, and even rival candidates should treat a candidate's faith as a matter of public concern during an election, and candidate's who are sincere about their faith and influenced by its teachings do voters a service by being open about their faith. On the other hand, if a candidate is only marginally affiliated with a religious faith and is not markedly influenced by its teachings, then his or her religious affiliation is probably not a matter of public concern and is best treated as a private matter.
All quotations from Martin Luther are taken from: John Dillenberger, ed. Martin Luther: Selections from His Writing. (New York: Anchor Books, 1962).
Samuel Popkin. The Reasoning Voter: Communication and Persuasion in Presidential Campaigns. (Chicago: University of Chicago, 1991).