WASHINGTON — Chief Justice John Roberts appears to hold the key vote over whether the Supreme Court will allow the nation’s first publicly funded religious charter school in Oklahoma.

Roberts was the only justice whose vote seemed in doubt after the court heard more than two hours of arguments Wednesday in a major culture-war clash involving the separation of church and state.

The court seemed otherwise deeply divided.

Four other conservative justices seemed firmly on the side of the St. Isidore of Seville Catholic Virtual School and the state charter school board that approved it.

“They’re not asking for special treatment, not asking for favoritism,” Justice Brett Kavanaugh said. “They’re just saying, ‘Don’t treat us worse because we’re religious.”

The three liberal justices seemed just as likely to vote to affirm an Oklahoma Supreme Court ruling that held that the taxpayer-funded school would entangle church and state in violation of the First Amendment.

Justice Amy Coney Barrett recused herself without explanation. Barrett previously taught law at Notre Dame and is close friends with Notre Dame law professor Nicole Garnett, a leading proponent of publicly funded religious charter schools.

If Roberts sides with the liberals, the court would be tied 4-4, an outcome that would leave the state court decision in place, but would leave the issue unresolved nationally.

If he joins his conservative colleagues, on the other hand, the court could find that the taxpayer-funded school is in line with a string of high court decisions that have allowed public funds to flow to religious entities. Those rulings were based on a different part of the First Amendment that protects religious freedom.

Roberts wrote the last three of those decisions. He acknowledged at one point that the court had previously ruled that states “couldn’t exclude religious participants,” suggesting support for St. Isidore.