The U.S. Supreme Court ruled on Friday in favor of Christian and Muslim parents in Maryland who sued to keep their elementary school children out of certain classes when storybooks with LGBT characters are read in a high-profile case involving the intersection of religion and LGBT rights.

The justices in a 6-3 ruling overturned a lower court's refusal to require Montgomery County's public schools to provide an option to opt out of these classes. The lower court had rejected the argument made by a group of parents who sued the school district that its policy prohibiting opt-outs violated the Constitution's First Amendment protections for the free exercise of religion.

"Today, we hold that the parents have shown that they are entitled to a preliminary injunction. A government burdens the religious exercise of parents when it requires them to submit their children to instruction that poses 'a very real threat of undermining' the religious beliefs and practices that the parents wish to instill," wrote conservative Justice Samuel Alito, who authored the decision.

The court's conservative justices were in the majority and its liberal justices dissented from the ruling.

The court has expanded the rights of religious people in several cases in recent years, including in cases involving LGBT people. For instance, the court in 2023 ruled that certain businesses have a right under the First Amendment's free speech protections to refuse to provide services for same-sex weddings.

The school board in Montgomery County approved in 2022 a handful of storybooks that feature LGBT characters as part of its English language-arts curriculum in order to better represent the diversity of families living in the county.

The storybooks are available for teachers to use "alongside the many books already in the curriculum that feature heterosexual characters in traditional gender roles," the district said in a filing.

The district said it ended the opt-outs in 2023 when the mounting number of requests to excuse students from these classes became logistically unworkable and raised concerns of "social stigma and isolation" among students who believe the books represent them and their families.

Opt-outs are still allowed by the district for sex education units of health classes.

The plaintiffs - who are Muslim, Roman Catholic and Ukrainian Orthodox - said in their lawsuit that the storybooks "promote one-sided transgender ideology, encourage gender transitioning and focus excessively on romantic infatuation - with no parental notification or opportunity to opt out."

They said the First Amendment protects their right to instill religious beliefs and practices in their children, including on gender and sexuality that are "crucial for their children's ability to fulfill religious aspirations concerning marriage and family."

Represented by the Becket Fund for Religious Liberty conservative legal group, the parents who sued included Tamer Mahmoud, Enas Barakat, Chris Persak, Melissa Persak, Jeff Roman and Svitlana Roman, along with an organization called Kids First that seeks opt-out rights in Montgomery County.

The Richmond, Virginia-based 4th U.S. Circuit Court of Appeals in 2024 denied a request by the plaintiffs for a preliminary injunction. The 4th Circuit said that there was no evidence that the storybooks are "being implemented in a way that directly or indirectly coerces the parents or their children to believe or act contrary to their religious faith."

The plaintiffs told the Supreme Court that the 4th Circuit's decision undermined the right of parents to "protect their children's innocence and direct their religious upbringing."

The school board emphasized in a brief to the court that mere exposure to content that parents find religiously objectionable does not violate the First Amendment.

The Freedom From Religion Foundation secularism advocacy group in a filing to the Supreme Court supporting the school board said parents should not have the constitutional right "to ensure that all secular education materials conform with their personal religious beliefs."

Such a rule would be boundless because "almost any book or idea - however commonplace or innocent - likely contradicts some religious ideals," the group said.

The Supreme Court heard arguments in the case on April 22. The court's three liberal justices raised concerns about how far opt-outs for students could go beyond storybooks in public schools, offering examples of subjects such as evolution, interracial marriage or women working outside the home that might come up in classes.

During the arguments, conservative Justice Samuel Alito cited one of the disputed storybooks that portrays a same-sex wedding and emphasized that the material promotes a moral message "that a lot of people who hold on to traditional religious beliefs don't agree with."

In another religious rights case involving education, the Supreme Court in a 4-4 ruling on May 22 blocked a bid led by two Catholic dioceses to establish in Oklahoma the first taxpayer-funded religious charter school in the United States.