FORTUNATELY, no one is going to follow Newt Gingrich’s unconstitutional and un-American plan for an inquisition to “test every person here who is of a Muslim background” and deport the ones who “believe in Shariah.” Even Mr. Gingrich himself, a day after suggesting this policy in the wake of the terrorist attack in Nice, France, conceded that such a plan was impossible. But his proposal is a reminder of a persistent and inexcusable misunderstanding of what Shariah is, both in theory and in practice.

Put simply, for believing Muslims, Shariah is the ideal realization of divine justice — a higher law reflecting God’s will.

Muslims have a wide range of different beliefs about what Shariah requires in practice. And all agree that humans are imperfect interpreters of God’s will. But to ask a faithful Muslim if he or she “believes in” Shariah is essentially to ask if he or she accepts God’s word. In effect, Mr. Gingrich was proposing to deport all Muslims who consider themselves religious believers.

Start with a crucial distinction. Shariah doesn’t simply or exactly mean Islamic law. Properly speaking, Shariah refers to God’s blueprint for human life. It is divine and unchanging, reflecting God’s unity and perfection. It can be found in God’s revealed word in the Quran and in the divinely guided actions of the Prophet Muhammad.