OKLAHOMA CITY — Oklahoma’s top education official ordered public schools Thursday to incorporate the Bible into lessons for grades 5 through 12, the latest effort by conservatives to incorporate religion into classrooms.

The directive drew immediate condemnation from civil rights groups and supporters of the separation of church and state, with some calling it an abuse of power and a violation of the U.S. Constitution.

The order sent to districts across the state by Republican State Superintendent Ryan Walters says adherence to the mandate is compulsory and “immediate and strict compliance is expected.”

“The Bible is an indispensable historical and cultural touchstone,” Walters said in a statement. “Without basic knowledge of it, Oklahoma students are unable to properly contextualize the foundation of our nation which is why Oklahoma educational standards provide for its instruction.”

Oklahoma law already explicitly allows Bibles in the classroom and lets teachers use them in instruction, said Phil Bacharach, a spokesman for state Attorney General Gentner Drummond.

But it’s not clear if Walters has the authority to mandate that schools teach it. State law says individual school districts have the exclusive authority to decide on instruction, curriculum, reading lists, instructional materials and textbooks.

The head of the Oklahoma chapter of the Council on American-Islamic Relations criticized the directive as a clear violation of the Constitution’s establishment clause, which prohibits the government from “establishing” a religion.

“We adamantly oppose any requirements that religion be forcefully taught or required as a part of lesson plans in public schools, in Oklahoma, or anywhere else in the country,” Adam Soltani said in a statement.

“Public schools are not Sunday schools,” said Rachel Laser, president and CEO of Americans United for Separation of Church and State, in a statement. “This is textbook Christian Nationalism: Walters is abusing the power of his public office to impose his religious beliefs on everyone else’s children. Not on our watch.”

Laser said the group was “ready to step in and protect all Oklahoma public school children and their families from constitutional violations of their religious freedom,” adding “public schools may teach about religion, but they may not preach any religion.”

Stacey Woolley, the president of the School Board for Tulsa Public Schools, which Walters has threatened to take over, said she had not received specific instructions on the curriculum, but believed it would be “inappropriate” to teach students of various faiths and backgrounds excerpts from the Bible alone, without also including other religious texts.

The efforts to bring religious texts into the classroom are part of a growing national movement to create and interpret laws according to a particular conservative Christian worldview.

The Oklahoma directive is likely to provoke the latest tangle over the role of religion in public schools, an issue that has increasingly taken on national prominence. It is the latest salvo in an effort by conservative-led states to target public schools: Louisiana has required them to post the Ten Commandments in classrooms, while others are under pressure to teach the Bible and ban books and lessons about race, sexual orientation and gender identity.

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 scheduled to open in August. The Oklahoma Supreme Court ruled against the school this week, but the decision is likely to be appealed.

Walters, a former history teacher who served in the Cabinet of Gov. Kevin Stitt before being elected state superintendent in 2022, has emerged as a lightning rod of conservative politics in Oklahoma and an unapologetic culture warrior in education. He has battled over the teaching of race and gender identity, fought against “woke ideology” in public schools and at times targeted school districts and individual teachers.

A former public school teacher who was elected to his post in 2022, Walters ran on a platform of banning books from school libraries and getting rid of “radical leftists” who he claims are indoctrinating children in classrooms.

He has clashed with leaders in both parties for his focus on culture war issues, and in January he faced criticism for appointing a right-wing social media influencer from New York to a state library committee.

Information for this article was contributed by Sean Murphy of The Associated Press and Sarah Mervosh of The New York Times.