If one studies the issues, I think it can be seen in general that Christianity, properly understood, is a religion for all peoples. What I mean is that Christianity does not necessarily overthrow a culture but may instead redeem it. Of course there may be some cultures that are so debased that, once a majority becomes converted, an overthrow to the previous way of life may occur. We see this a few times in the book of Acts where certain religious businesses come into conflict with people not purchasing their idolatrous fixes. However, Islam is simply not that way. Islam seeks to overthrow cultures and convert the world to 7th century Islam. That is what Sharia Law is all about.
This paragraph offers the initial question being discussed.
The conflict between religious imperatives and the legal obligations one has as a citizen of a secular state — a state that does not take into account the religious affiliations of its citizens when crafting laws — is an old one (Scalia is quoting Reynolds v. United States, 1878); but in recent years it has been felt with increased force as Muslim immigrants to Western secular states evidence a desire to order their affairs, especially domestic affairs, by Shariah law rather than by the supposedly neutral law of a godless liberalism. I say “supposedly” because of the obvious contradiction: how can a law that refuses, on principle, to recognize religious claims be said to be neutral with respect to those claims? Must a devout Muslim (or orthodox Jew or fundamentalist Christian) choose between his or her faith and the letter of the law of the land?
Now obviously we have seen Baptists stand for Prohibition, and so Christians are often supposedly forced to choose either the State's Law or God's (I guess God is against wine). However, this is a false dichotomy that Christians have disagreed upon. But what about the issue of Abortion or slavery. Although Christians also disagree on these issues, to argue that the State may remain neutral would be absurd on its face. But again, we are talking about fundamental issues and the basis for the rule of law.
So Fish's question is correct,
...how can a law that refuses, on principle, to recognize religious claims be said to be neutral with respect to those claims?
This is a great question and the answer that Christianity has offered since the Reformation has been the solution...for the most part. The answer that Christ and His Apostles give is that Christ's Kingdom is not of this world. Therefore, the two are not the same Kingdom. Therefore, the specific beliefs of Christians that pertain to the church and her ordinances are not to be confused with the State.
This is where the difficulty lies for Christians. The State is not "neutral". If the Christian faith is correct, then we must all acknowledge that God is the one who institutes the State. Now obviously, not everyone is a Christian, so how can this work? Though this seems troubling to many, it is actually the best part of our system of government. We all have a voice in the public sphere. The Christian is free to argue that abortion or slavery (as practiced in the South) is wrong. And he may do so on the basis of religion's revelation. If he is able to persuade his fellow man, then so be it.
Sharia law is simply not the same. In Islam, there is no such thing as a separation of Church and State. By definition, there can not be a separation.
Fish offers an example of Reverend Rowan Williams, Archbishop of Canterbury's
suggestion others had made before him) that in some areas of the law a “supplementary jurisdiction,” deriving from religious law, be recognized by the liberal state, which, rather than either giving up its sovereignty or invoking it peremptorily to still all other voices, agrees to share it in limited areas where “more latitude [would be] given in law to rights and scruples rooted in religious identities.
The solutions offered by religious scholars seem problematic as Fish notes,
The words to stumble on are “reasonable” and “just,” which at once introduce the requirement and indicate how hard, if not impossible, it will be to meet it: “reasonable” means confirming to rational, not religious, principles; “just” means respecting the equality of all, not just male or faithful, individuals.
How can laws be based upon such an idea if Islam is not able to keep their "reasonable" laws from harming those who would disagree with them? As I said earlier, Christianity has a solution to this dilemma. Islam does not and sees no need for one.
Fish cites Milbank as arguing that Christianity has the ability to show respect for Islam where a secular liberal state can not. In the end, I don't see that Fish really comes to a solution. It seems to me he is on the right path in acknowledging Christianity as a solution, but I am not certain if he sees the "Two-Kingdom" model as a part of his terminology?
My personal opinion is that perhaps the term "secular" needs to be more carefully defined. Whenever I have this conversation with atheists, at first they seem to like the idea of my understanding of Church and State. The problem always arises when the definition of secular, as being applied to the State, comes in to play. I reject that secular has to mean "Godless". At the same time, I don't think Christians need to argue a particularly Christian (ie Baptist, Presbyterian) position to persuade his fellow man of the "Laws of Nature and Nature's God". The problem, however, will become reversed. Instead of the State being hostile to religious claims, it will be seen as hostile to the atheist.
The truth is that this is God's world. He is the Creator of all things as Fish rightly points out that a so-called Christian worldview has a "teleological view of history notably lacking in liberalism". So once again, our nation is going to have to go back and rethink these issues in light of Islam. Do we go back to a definition of secular that the Founders would have embraced? And if so, how can we as a nation embrace an immigrant Islamic people that fundamentally, must overthrow our way of life.