Religious liberty has become a particularly politicized topic in recent years, and recent months were no different. In a long-awaited June decision , the Supreme Court decided in favor of a Christian baker who refused to make a custom wedding cake for a gay couple. In July, Attorney General Jeff Sessions introduced a “religious liberty task force” that critics saw as a mere cover for anti-gay discrimination. And Judge Brett Kavanaugh’s record has been scoured for evidence of what his appointment to the Supreme Court would mean for future decisions in which Christian beliefs clash with law and policy.

But when it comes to religious liberty for Americans, there’s a disturbing trend that has drawn much less attention. In recent years, state lawmakers, lawyers and influential social commentators have been making the case that Muslims are not protected by the First Amendment.

Why? Because, they argue, Islam is not a religion.

This once seemed like an absurd fringe argument. But it has gained momentum. John Bennett, a Republican state legislator in Oklahoma, said in 2014, “Islam is not even a religion; it is a political system that uses a deity to advance its agenda of global conquest.” In 2015, a former assistant United States attorney, Andrew C. McCarthy, wrote in National Review that Islam “should be understood as conveying a belief system that is not merely, or even primarily, religious.” In 2016, Michael Flynn, who the next year was briefly President Trump’s national security adviser, told an ACT for America conference in Dallas that “Islam is a political ideology” that “hides behind the notion of it being a religion.” In a January 2018 news release, Neal Tapio of South Dakota, a Republican state senator who was planning to run for the United States House of Representatives, questioned whether the First Amendment applies to Muslims.

The idea that Islam, which has over 1.6 billion adherents worldwide, is not a religion was even deployed in a 2010 legal challenge of county approval of building plans for a mosque in Murfreesboro, Tenn. The plaintiffs argued that Islam is not a religion but rather a geopolitical system bent on instituting jihadist and Shariah law in America. Because Islam is not a religion, the argument went, the mosque construction plans should not benefit from the county or federal laws that protect religious organizations. The local court ruled against the mosque, but the Tennessee appellate court overturned the ruling and the mosque prevailed.