Oklahoma’s state superintendent on Thursday directed all public schools to teach the Bible, including the Ten Commandments, in the latest conservative push testing the boundaries between religious instruction and public education.

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

“The Bible is a necessary historical document to teach our kids about the history of this country, to have a complete understanding of Western civilization, to have an understanding of the basis of our legal system,” Mr. Walters, a Republican, said in his announcement, adding that “every teacher, every classroom in the state will have a Bible in the classroom.”

The directive is likely to be challenged in court and could provoke the latest tangle over the role of religion in public schools, an issue that has increasingly taken on national prominence.

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

Oklahoma had also sought to be the first state to authorize a religious charter school, which would have funneled taxpayer dollars to an online Catholic school slated to open in August. The Oklahoma Supreme Court ruled against the school this week, but the decision is likely to be appealed.

This is a developing story. Check back for updates.