The Establishment Clause of the First Amendment is clear about forbidding Congress from passing laws that mix the business of the state with matters of religion. Yet Republican lawmakers, many of whom are lawyers and constitutional scholars, seem intent on delving into matters of religion anyway from their Capitol Hill and statehouse pulpits. A major warning sign of Republicans’ refusal to honor the Establishment Clause was when Missouri Gov. Mike Parson listed sharing his own “Christian values” as a requirement for his nominee as state health director. Now comes Sen. Lindsey Graham of South C…