The Supreme Court’s upcoming abortion- and guns-rights cases are getting much of the attention right now, but a third, relatively overlooked case could transform one of the most consequential areas of American law: the separation of Church and state. If the plaintiffs win, states and municipalities could be required to use taxpayer dollars to supplement strands of private religious education that many Americans would find deeply offensive, including schools that exclude non-Christian or LGBTQ students, families, and teachers.