Over on his CFI blog, It's Only Natural, John Shook addresses an argument against religious freedom. The view that he challenges is articulated like this in a piece on the American Catholic blog:
there is a built in contradiction in the place of religious freedom in classical liberalism: While religious freedom is a central element of classical liberalism, the ability of a state to function as a liberal democracy will collapse if a large majority of the population do not share a common basic moral and philosophical (and thus by implication theological) worldview. Thus, while religious freedom is a foundational element of classical liberalism, only a certain degree of religious conformity makes it possible.
Now, before going any further, I must observe what a recipe for intolerance and bigotry this is. I'll try to discuss it dispassionately in the paragraphs that follow, but you can be assured that I fully appreciate that it's morally repellent.
How does Shook respond? Quite sensibly - for example, by emphasising that what is required is not theological consensus but some degree of basic moral/philosophical consensus. As he says, these are not the same thing.
But that actually understates it. Sure, there has to be some consensus that we cannot, for example, just go around using violence to promote our own interests in social, economic, and sexual competition. The benefits of social life will be impossible unless there are some strong norms against that kind of violence. Given the scarcity of resources, there also has to be some sort of property system; whatever form this takes, it will need to be experienced as "fair" (in practice, this is likely to involve such things as some emphasis on effort and contribution in acquisition, while also a place for property to be transferred as a gift); and there will need to be a strong norm that property rights be honoured (which does not preclude, and may even require, the overlay of a scheme of taxes and transfers based on need and other relevant values). This level of basic agreement on certain sorts of legal and moral norms is, in fact, required for any society to operate. However, the reasons have nothing to do with theology and can be agreed to from almost any comprehensive worldview. Whatever their comprehensive worldview, nobody wants to live in a Hobbesian state of nature.
Generally speaking, we all have good secular reasons to support these sorts of norms and to socialise children into internalising them. Theology has nothing to do with it.
When it comes to issues such as whether homosexuality or polyamory or abortion or stem cell research or the use of contraception or IVF or reproductive cloning is morally wrong, however, the situation changes. It is not necessary for social survival and the benefit of living in societies that there be agreement on these things. The law can allow somebody who thinks one of these things is morally wrong to refrain from it, while also allowing those who have no such moral aversions, and who find these things good, to act on their own beliefs. In such a case, neither group of people is subjected to tyranny. The former are not subjected to tyranny because they are not forced to do anything that goes against their own morals. It would be a bizarre definition of "tyranny" to say that someone is tyrannised merely because she is powerless to stop others doing things she disapproves of. The latter group - the homosexuals, polyamorists, women seeking abortions, etc., are not tyrannised either. They are not prevented from doing what they want. (They might be tyrannised if their activities are legal but nonetheless lead to social ostracism, but in a society where there actions are not only legal but approved of by large numbers of people they cannot claim to be tyrannised. If social tyranny is too much of a problem, some specific laws may need to be enacted to ensure they can function in society.)
Human societies can certainly operate with no theological consensus, so long as there is even a fairly rough consensus on the norms required to protect such worldly things as life, limb, and property. Someone with a theologically-based morality may wish to see many things prohibited that are actually allowed, but she cannot complain merely because she doesn't get to use the state apparatus to control what others do. If she wants more than that, the rest of us may rightly regard her as unreasonable - she wants her own way not only in how she gets to behave but also in forcing others to do likewise.
Stook deals with a further argument:
If, however, there is fundamental disagreement among the populace about basic issues of right and wrong and what the purpose of the human person is, the victory of the other side will increasingly look to the defeated like an unacceptable tyranny, and the state will risk coming apart at the seams.
His reply is that this is essentially a fantasy, as no such fundamental disagreement is actually tearing apart the country that both bloggers are talking about, i.e. the United States of America. But I'd go further. It is quite possible for a society to get along with fundamental disagreements about such things as "what the purpose of the human person is". You could have half the population claiming that the purpose of the human person is to worship a particular god, while the other half denies that there is any "purpose" at all (though they may still think that life can be rich, personally meaningful, lived with zest, and so on). There is no reason at all why these two groups cannot co-exist in the same society. All that is required is that neither attempt to coerce the other to live in a certain way. They will, of course, also have to have some consensus about the need to refrain from violence, respect property rights (and legitimate redistributions of property through the official tax-transfer system) and so on. But that's already covered above.
In other words, it is indeed possible to have a state that does relatively limited things - protecting us from internal and external violence, establishing and enforcing a scheme of property, imposing taxes and redistributing wealth in the form of public programs based on such things as individual need - without anyone having to feel defeated or tyrannised. Of course, you may literally be defeated if you campaign for, say, the criminalisation of homosexual acts ... and your pet theologically-based campaign fails. But your "defeat "simply means that you have failed to coerce others, or to get the state to do it for you. It is bizarre to claim that you are, yourself, being tyrannised.
If your views are based on religious doctrine, you will have failed to impose your religious morality on others who don't share it. That does not, however, mean that they are tyrannising you or that your freedom to live by your own religious morality has been lost.
There are, of course, any number of complexities and ramifications to all this, but if there is any contradiction in classical liberalism, or in freedom of religion, the arguments that Stook refers to certainly do not establish it. Of course, as with almost anything in this domain, there are going to be some grayish areas, but some can be dealt with in a principled way, while others can be dealt with by means of the reasonable discretion of electorates and governments. Overall, the view of the world sketched above can be elaborated indefinitely to cope with real-world complications, and I see no reason why it should ever come apart - at least not under pressure from the crude arguments dissected in this post.