Texas education officials on Friday approved a new elementary school curriculum that draws from the Bible, the final step of a contentious effort to expand religious instruction in the state.

The reading and language arts curriculum, which will be optional for schools, could serve as a model for conservative Christian leaders in other states. Its approval came as Oklahoma’s superintendent seeks to compel all educators to teach from the Bible, and as Louisiana fights in courts to require the Ten Commandments to be displayed in classrooms.

Starting in August, the new Texas curriculum, for kindergarten through fifth grade, will be available to districts. The state serves more than two million elementary students in its public schools.

The curriculum incorporates into English lessons stories from the Bible such as Jesus and his Sermon on the Mount, the parable of the Prodigal Son and the Old Testament tale of Esther.

It has ignited a fierce backlash. Hundreds of Texans protested for months at meetings of the State Board of Education, which sets standards for what students are taught and approves a range of materials. The state’s largest teachers’ union and many parents — including some Christians — argue that the lessons blur the line between instruction and proselytizing, and present scripture as factual truth to children as young as 5.

But Gov. Greg Abbott, a Republican, and other supporters of the new program say that the Bible is a fundamental text in American history and that students’ reading comprehension will suffer without a robust knowledge of its stories and themes.