On Tuesday, voters in Alabama passed a ballot measurethat, among other things, forbids courts, arbitrators, and administrative agencies from applying or “enforcing a foreign law if doing so would violate any state law or a right guaranteed by the Constitution of this state or of the United States.” Such measures (other states have passed similar laws) are often dubbed “anti-Sharia” measures since preventingthe encroachment of Sharia is usually their primary objective.

Sharia is the moral code and religious law of Islam that deals with topics addressed by secular law, including crime, politics, and economics, as well as personal matters such as sexual relations, hygiene, diet, and prayer. The two primary sources of Sharia law are the Quran and the example set by the founder of Islam, Muhammad. The introduction of Sharia across the globe is a longstanding goal for Islamist movements.

Opposing Sharia law may appear to monsensical measure. But such laws are unnecessary since state law and the Constitution already trump foreign law. They also can’t be written to oppose only Sharia (that would be religious discrimination) so they are written in a broad way that has unintended consequences.

Indeed, there is pelling reason why Christians should be leery of joining in supporting anti-Sharia legislation: By helping to push the idea that religious beliefs should be kept private, anti-Sharia laws are a threat to all of our religious liberties. As the Catholic legal scholar Robert K. Vischer explained last year in First Things:

Though popular with secularists and religious conservatives, anti-Sharia legislation does not defend against theocracy but calls into question our society’s mitments to meaningful religious liberty and meaningful access to the courts. mitments have been relied on by generations of Protestants, Catholics, Mormons, and Jews, and to try to remove them for Muslims both is unjust to Muslims and sets a dangerous precedent for other religious groups.

[. . .]

Before Christian and Jewish believers support such measures, they should consider the way these laws not only misunderstand the faith of their Muslim fellow citizens but threaten their own religious liberty. Muslim Americans who seek to use Sharia are not asking the American legal system to adopt Islamic rules of conduct, penal or otherwise. Muslims have introduced Sharia in court not in an attempt to establish a freestanding source of law binding on litigants but rather in recognition of the norms to which the litigants have already agreed to be bound.

American courts do this every day—it’s called contract law. Even the literature being pumped out by anti-Sharia organizations shows that their target is not the threat posed by the imposition of Sharia on American society but rather the threat posed by the introduction of Sharia according to the same criteria of admissibility applied by courts to other religious codes.

Vischer gives an example of a Baptist church, whose rules may state that a pastor can be removed only by a vote of the entire membership. If the court determines that a small group of members ousted the pastor without the required vote, the court will uphold the pastor’s challenge despite the fact that the rules are based on a mitment (i.e., the mitment to the priesthood of all believers).

Another example is when courts enforce arbitration agreements based on biblical principles pursuant to widely invoked rules of “Christian conciliation.” To exclude similar agreements between Muslims that are based on Islamic principles would be to violate their freedom of religion — and set a precedent that could jeopardize the religious liberty of Christians.

As Vischer adds, “the presumption that the deepest core values and convictions of religious Americans threaten the legal order by virtue of their source, without reference to their substance.” If we don’t want biblical principles to be terms excluded from American court system, we shouldn’t rush to support such ballot measures.