The Supreme Court ruled Friday that schools violate religious liberty when they bar parents from opting their children out of classroom instruction involving LGBT-themed books, a major win for religious conservatives.

Justices voted 6-3 along ideological lines to back a group of religious parents affiliated with Montgomery County Public Schools in Maryland who argued they should be able to opt their children out of lessons with LGBT themes.

Justice Samuel Alito penned the opinion, writing that the school district burdened the parents’ First Amendment rights.

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“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,” Alito wrote.

Rosalind Hanson, one of the plaintiffs in the case, said she is “thrilled” with the decision.

“I am thrilled with the Supreme Court’s decision to uphold religious liberty and parental rights against our authoritarian school district pushing a one-sided agenda,” Hanson told The Daily Wire.

“Our children should never have been forced to learn about such sensitive topics without the ability for parents to know or opt them out,” said Hanson, who also chairs the Moms for Liberty Chapter in Montgomery County.

Parental rights advocates and religious groups celebrated Friday’s decision.

“Storybooks like those at issue in Mahmoud convey normative messages on sex and gender, and those messages can and often do conflict with the beliefs of parents and their children,” said Sarah Parshall Perry, vice president and legal fellow at Defending Education.

“Today’s ruling should act as a directive to every American school district: notify parents of controversial material, and provide them the opportunity to opt their children out — especially if you provide opt-outs for other curriculum or other reasons,” Perry said.

Kelsey Reinhardt, president and CEO of CatholicVote said the case was a “major victory” but that it should “alarm every American” that the high court had to step in.

“For over two years, Catholic parents alongside parents of other faiths have been forced to defend their constitutional right to opt their pre-K-8th grade children out of radical LGBTQ+ course materials that contradict their own religious beliefs,” Reinhardt said, adding that Montgomery schools “insisted on forcing explicit curriculum about gender ideology on children as young as 3 years old.”

“The Court’s ruling sends a clear and powerful message: America still respects the rights of parents to raise their children in line with their faith and conscience,” she said.