Few issues are more controversial than the proper role of religion in politics. In my recent book, Liberal Politics and Public Faith: Beyond Separation, I have attempted to develop a genuinely liberal approach to religion in the political life of democratic societies, one that preserves a robust sphere for personal freedom, respects religious and secular persons as equals, and prohibits the state from promoting a particular vision of the holy, the true, or the good. To make my case, I begin by contrasting my approach with three more familiar alternatives: I term these the libertarian, religious conservative and secular progressive views about religion in politics.
I. The Libertarian Approach
Given the venue, I begin by assessing the libertarian approach, or more accurately, what I see as libertarians’ lack of an approach to religion in politics.
The view I most often encounter is that religious belief is dangerous and should be excluded from politics. Objectivists are most aggressive on this front. But the more general attitude is that religion in politics is uninteresting because democratic politics should be dramatically weakened or abolished; private property alone will then answer these questions. This attitude is based on a principled form of property-rights reductionism, where all that matters is whether property rights are being respected or violated. This view is a manifestation of thin libertarianism, which is probably still the dominant position in the liberty movement. The father of this approach was Murray Rothbard, who across his massive corpus of theory and commentary never penned a single piece developing a systematic libertarian approach to religion in public life. He may not have thought it necessary.
The libertarian approach has two virtues in contrast to other common approaches. First, it does not make an idol of politics. Libertarians do not use politics to either establish religion or denigrate it. Second, libertarians recognize that much political participation amounts to little more than in-group bias and morally unappealing signaling.
The weakness of the libertarian approach is that it confuses politics and the state. Libertarians frequently forget that any free society is going to have both political disputes and deeply religious citizens. Politics and religion are not going away even if the state is abolished. And the role of religion in politics directly affects how any political process respects or violates liberty. If we are to ever have a libertarian society, we must find a way to speak to these conflicts. As Deirdre McCloskey has taught the liberty movement, rhetoric matters because it affects the structure of social and political culture. If we are to promote a culture of liberty, we need to figure out which forms of discourse are compatible with that culture and which are not. Libertarians, in short, need a theory of the public sphere.
II. The Religious Conservative Approach
Religious conservative approaches to religion in politics are typically establishmentarian. Religious conservatives across many societies, including democratic ones, seek some favored social or political status for their preferred religious view. In the United States, this often takes the form of civic theism – the view that good governments acknowledge God’s existence, His moral authority, and the objectivity of morality as rooted in His commands. The attempt to display the Ten Commandments in public spaces is a paradigmatic example of civic theistic legal policy, though coercive laws play a role as well, such as those that ban same-sex marriage.
The problem with the religious conservative approach is that giving a single religious view special political status is unfair to non-believers. Establishmentarian political policies fail to respect the equality of all persons by promoting some views and not others. Worse, some establishmentarian policies violate the rights of non-believers, as with attempts to interfere with science education in mandatory public schooling. Both believers and non-believers have a right to educate their children as they think is best. Mandating intelligent design interferes with this.
But there are also good religious reasons to oppose establishmentarian policies. As a theologically orthodox Christian, I don’t want the state to give my religion special political status. Historically, states have bent Christianity to support their own power and have distorted its doctrines and ecclesiastical structure. But more importantly, I don’t want my non-Christian friends to be treated as second-class citizens on Christian grounds. I believe that Jesus taught that all human beings, no matter who they are, are both loved by God and made in His image, and so have a dignity that demands respect.
Many of my conservative Christian friends and family will wonder why I’m opposed to having my nation honor God in its practices, but I don’t think a society can truly honor God by diminishing the social and political status of non-Christians. I think everyone has good reason, Christian or no, to reject the religious conservative approach.
III. The Secular Progressive Approach
The secular progressive approach reigns among intellectuals and theorists. It is this approach I critique in my book.
The secular progressive approach claims to embrace equality and state neutrality. On these grounds, secular progressives oppose religious influences in politics. Religious political activism violates our understanding of democratic politics as a shared enterprise of promoting mutually acceptable policies. Treating others with equal respect in politics requires appealing to reasons whose force all can appreciate. Since not everyone is religious, no religious reasons are shared reasons. Consequently, good citizens do not appeal to religious reasons. Instead, they confine themselves to shared reasons when supporting political policies and discussing them with others. In this way, secular progressives assign religious reasoning an auxiliary role in public life, at best. This leads progressives to support a more private role for religious belief and commitment in general, a privatization of religious belief.
This line of argument has two problems. First, it leads to the marginalization of sincere citizens of faith. Secular progressives imply that deeply religious citizens have less civic virtue than secular citizens and insist that they bear heavier political burdens. Second, privatization requires many religious citizens to violate their personal integrity. To be good progressive citizens, many religious people must subordinate their religious commitments to the secular democratic state, which many cannot do in good conscience.
Because the secular progressive approach both marginalizes many sincere citizens of faith and demands that they violate their own integrity in public life, the secular progressive approach resembles the establishmentarian policies defended by religious conservatives. Whether they realize it or not, secular progressives seek to establish secularism as the de facto if not official ruling ideology of democratic states by insisting on a conception of political life that excludes many people of faith. In France, at least, the establishment of secularism is widely acknowledged and accepted. In the United States, secular progressives have been more circumspect.
IV. A Classical Liberal Approach
The problem with religious conservatism is its penchant for establishment. Secular progressives have the same authoritarian aim but are generally in denial about it. Libertarians lack any constructive theory of politics and the public sphere, though they rightly demythologize political life and are much more realistic about the prospects for constructive public discourse.
So what we need is an approach to religion in politics that is fundamentally constructive and anti-establishmentarian. This approach should preserve religious liberty and take a strong stand on the importance and/or dangers of religious contributions to politics. In my book, I argue that laws are only justified when multiple reasonable points of view find them acceptable. Diverse reasons, including but not limited to religious reasons, can play a prominent role in public discourse. Given that non-religious citizens and citizens of other faiths will reasonably reject nearly all religiously based coercion, religious reasons will seldom be sufficient to justify laws or policies by themselves. However, religious reasons will be able to defeat many laws and policies on religious grounds.
To illustrate my approach, consider how I apply it to same-sex marriage and the contraception mandate.
1. Same-Sex Marriage
Conservatives regularly attempt to legally define marriage as a union between one man and one woman. Let’s assume for the sake of argument that conservatives have both successful (but not indubitable) natural law arguments that explain why heterosexual marriage is the only morally permissible form of conjugal union and successful (but not indubitable) theological arguments that only a man and a woman can count as married in God’s eyes. On the theory I advance, these arguments cannot justify restricting marriage to a man and a woman given that such laws force many organizations to deny benefits to gay couples that would otherwise offer them. This is because many people, religious and secular, can reasonably reject even good conservative arguments.
On the other hand, legalizing gay marriage without religious exemptions disrespects sincere citizens of faith by forcing them to provide benefits to gay couples whose unions they reasonably believe are morally and theologically invalid. Thus, my approach either requires the abolition of government marriage, or as a second best policy, the legalization of gay marriage with extensive religious exemptions. These two policies are the only way to respect the diverse reasoning of all concerned parties.
2. The Contraception Mandate
The contraception mandate, created by the Department of Health and Human Services in order to fully implement the Affordable Care Act, originally required all employers, save religious organizations, to pay for contraception for their employees. When a wide range of religious institutions objected, the Obama Administration partly backed off, instead forcing religious for-profit institutions to offer contraception coverage and permitting non-profit religious employers to be exempt only if they signed a form that (arguably) authorizes a third-party insurer to provide contraception.
This mandate has been incredibly and needlessly divisive. There is no reason that the Obama Administration couldn’t have paid for contraception for women who need it in some other way. Instead, they have threatened non-profit religious institutions like Little Sisters of the Poor with massive fines unless they do what they believe is sinful – facilitating the use of contraception. This is the authoritarianism of the secular progressive approach made manifest.
Given that libertarian and conservative citizens have sufficient reason to reject many of the ACA’s main provisions, it is not even clear that the ACA itself can be justified to multiple, reasonable points of view. But even if the ACA can be so justified, the contraception mandate plainly cannot. Religious organizations have publicly offered highly sophisticated, well-reasoned and sincere arguments against the mandate drawing on hundreds of years of intellectual tradition. If religious reasons can serve as defeaters, as I argue, then a great many religious citizens have sufficient objection to defeat any justification for the contraception mandate, at least as it applies to them.
The role of religion in politics is to preserve religious liberty against an overreaching state and encourage religious contributions to the ratification of laws that promote justice and the common good. Religion belongs in politics primarily as defense, rather than offense, restricting state power rather than extending it. We can see this in my two examples. Religion in politics serves as a defeater for legislating traditional marriage and for legislating contraception provision by sincere religious objectors.
Further, a genuinely liberal approach to religion in politics permits political discourse and action as diverse as American citizens themselves. Our public discourse should be far more uninhibited than secular progressives allow, so long as people are prepared to acknowledge that there are legitimate points of view other than their own. The only forms of religious discourse that are truly illiberal are those that insist that one’s own reasoning is sufficient to justify coercing reasonable people who disagree. But the same is true of secular discourse! This means that for true liberalism, religion is not the problem; coercion is the problem.
The classical liberal approach to religion and politics, then, avoids both overt and covert establishmentarianism. It bars efforts to give a particular religion, or even religion generally, a hallowed place in the law, while simultaneously resisting efforts to remove religion from the public square. Given its focus on restricting unjustified coercion, my approach does not make an idol of politics and does not insist that shared public deliberation is the sine qua non of a free, democratic society. I submit, then, that it is superior to the three more familiar approaches, libertarian, conservative, and progressive.
 See “The Ten Commandments vs. America,” “Faith-Based Initiatives are an Assault on Secular Government,” and Peikoff’s “Religion vs. America.”
 And neither are unshared non-religious reasons: the secular progressive approach excludes many libertarian views as sectarian and unreasonable.
 Conservatives sometimes frame legalizing same-sex marriage as adding to marriage law, creating something new. In a way, this is true. But legalizing same-sex marriage in combination with religious exemptions reduces legal coercion by permitting organizations to extend benefits to same-sex couples. The “addition” framing obscures the fact that in many cases legalizing same-sex marriage is more akin to repealing a prohibition.
 For a related and thoughtful discussion, see http://www.cato.org/blog/republic-gilead-not-night