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

The directive sent Thursday to superintendents 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.”

The directive is the latest effort by conservative-led states to target public schools: Louisiana 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. Earlier this week the Oklahoma Supreme Court blocked an attempt by the state to have the first publicly funded religious charter school in the country.

A former public school teacher who was elected to his post in 2022, Walters ran on a platform of fighting “woke ideology,” 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 including transgender rights and banning books, and in January he faced criticism for appointing a right-wing social media influencer from New York to a state library committee.

Walters’ directive immediately came under fire from civil rights groups and supporters of the separation of church and state.

“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.”