There has been some controversy recently, because the Archbishop of Canterbury, no less, suggested that sharia law could in some ways be incorporated into the British law code. This suggestion created a certain amount of outrage; and in the last election the state of Oklahoma, not a state with a large number of Muslims, passed an initiative to declare that sharia law could not be incorporated into their state law. (I do not know whether Cherokee Law has been incorporated into their state law, which is a much more likely prospect historically.)
There is no need for this. And there is, interestingly enough, a Christian precedent. In First Corinthians 6, Paul informs the Corinthians that they are to settle legal disputes among themselves rather than take them to the “pagan courts.” This implies that there is sort of a “Christian sharia” or standard for settling these disputes that draws on Old Testament law and New Testament principles in addition to the civil law of the territory. There is no question, of course, of this “Christian sharia” being in any way endorsed or enforced by the government. Rather, the punishment was excommunication, or barring from the Communion table, or perhaps under certain circumstances even exclusion from the catechumens. (In another place in the same Epistle, Paul proposes that we can socialize with pagans who are greedy and adulterous, etc., but not with people who claim to be Christians and who act like that.) There is in fact a mini-drama carried out in the two Corinthian epistles of a man who is found to be sleeping with his stepmother, is excommunicated, and then, being repentant and having changed his lifestyle, restored. And a lot of the discussion in evangelical circles of “not suing your brother in court” presupposes the existence of an organized system of discipline in the church. The church is under no obligation to tolerate the presence of con men and the like in their midst. We may or may not sue them (if they are a danger to the public at large, taking civil or criminal action against them is allowable, “pagan courts” or not) but we should not allow them to pose as Christians in good standing. And not only that, Paul says that we can even “judge”! This sounds like a surprise to those who have a superficial knowledge of the teaching of Jesus, but I believe that Jesus is not forbidding us to say what behavior is right or wrong, acceptable or unacceptable. He is forbidding us to psychoanalyze and be too quick to assign motives or judgments about character to misbehaving people. And He is also informing us that we are falling short under the same standard!
So, by the same token, our Muslim friends have every right to apply sharia law within their own community. But the ultimate punishment they can use is excommunication from the mosque, or whatever their equivalent is. They cannot expect the state to enforce their rulings or their fatwas. They may not do “honor killings.” They have to respect the right of their young ladies to refuse to marry anyone they do not wish to marry. They have to respect the right of anyone to apostatize and leave the religion. They have to accept that once someone apostatizes, sharia law is no longer binding on him. The Amish, for example, lead a traditional life far more exotic than any Muslim group, but they accept these terms and nobody complains about them. Once again, as I think I have said before, because Christianity existed apart from political power for 300 years, though Christians have since abused power from time to time, Christianity has in its historical memory a knowledge of how to live when it is not in charge. For Islam, that is a very new thing.