Oklahoma’s state superintendent on Thursday directed all public schools to teach the Bible, including the Ten Commandments, in an extraordinary move that blurs the lines between religious instruction and public education.

The superintendent, Ryan Walters, who is a Republican, described the Bible as an “indispensable historical and cultural touchstone” and said it must be taught in certain, unspecified grade levels.

The move comes a week after Louisiana became the first state to mandate that public schools display the Ten Commandments in every classroom, which was quickly challenged in court.

The Oklahoma directive could also be challenged and is likely to provoke another fight over the role of religion in public schools.

The efforts to bring religious texts into the classroom reflect a growing national movement among conservatives — particularly Catholics and evangelicals who oppose abortion, transgender rights and what they view as liberal school curriculums — to openly embrace the idea that America’s democracy needs to be grounded in their Christian values.

That movement had a major victory in overturning Roe v. Wade two years ago, and its supporters see ending abortion as only a starting point in a broader campaign to preserve and expand the presence of their Christian values in American life. Many conservative Christians see schools as a frontier of their fight, as they seek to shape the next generation.