On Dec. 5, the U.S. Supreme Court will hear arguments in a case that could have a huge impact on how our nation’s anti-discrimination laws protect the LGBTQ community, religious minorities, women and just about anyone.

That’s why today Americans United filed a friend-of-the-court brief urging the high court to affirm that businesses like Masterpiece Cakeshop cannot use religious beliefs as justification to refuse to serve customers.

“Religious freedom is about fairness: We don’t treat people differently because their beliefs are different from ours,” said Richard B. Katskee, legal director of Americans United. “The U.S. Supreme Court has repeatedly found that the Constitution does not allow businesses to use religious beliefs as an excuse to treat some people like second-class citizens. We urge the justices to once again stand on the right side of history and advance the court’s noble tradition of ensuring equality for all Americans.”

In Masterpiece Cakeshop v. Colorado Civil Rights Commission, the Supreme Court will consider whether a Colorado baker could refuse to bake a wedding cake for Charlie Craig and David Mullins, a same-sex couple. A Colorado court held that the bakery’s refusal violated the state’s anti-discrimination laws, which prohibit discrimination based on sexual orientation. The bakery appealed that decision to the U.S. Supreme Court, claiming that its religious views entitle it to violate the law.

Masterpiece Cakeshop and other businesses should not be allowed to use religious beliefs as justification to refuse service to same-sex couples and other customers.

This is one of several cases nationwide in which wedding-related businesses are trying to claim a religious-based objection to marriage for same-sex couples as justification for refusing to serve LGBTQ people. Many of these businesses are represented by Alliance Defending Freedom (ADF), a Religious Right legal group that often defends people who want to discriminate using religion. Another of ADF’s clients, Arlene’s Flowers, has a petition pending before the Supreme Court for a case in which the florist refused to provide flowers for a same-sex couple’s wedding, in violation of Washington state’s civil-rights law. The florist is making the same argument as the baker: It wants to discriminate against same-sex couples in the name of religion.

These businesses seek “to turn America’s anti-discrimination laws upside down. We are fighting for the Constitution’s fundamental promise of fairness and equality,” said Katskee. “Allowing businesses to use religious beliefs as justification to refuse to serve customers would corrupt the principle of religious freedom and open a Pandora’s box of discrimination.

Not only does Masterpiece seek to discriminate against LGBTQ customers, but if the court accepts the business’s argument, it would open the door to discrimination against people due to their religious beliefs – the very thing the bakery purports to want to prevent.

That’s what we note in our brief: “(U)nequal treatment of, and denials of service to members of minority faiths, persons adhering to a different faith, and atheists are all too common. And religious discrimination, like other forms of discrimination, may be, and often is, premised on religious views or motivations. Hence, petitioners’ arguments for a religious exemption permitting denials of service to same-sex couples could also be advanced to support denials of service to people of marginalized faiths.”

Six civil-rights and religious organizations joined us in filing the brief today: the Anti-Defamation League, Bend the Arc: A Jewish Partnership for Justice, Fairness West Virginia, Interfaith Alliance Foundation, the National Council of Jewish Women and People For the American Way Foundation. We urge the Supreme Court to affirm the opinion of the Colorado court that found that the bakery has no right to violate antidiscrimination laws.

If businesses are granted a constitutional license to violate antidiscrimination laws, observes the brief, then any person “could be refused employment, thrown out of a hotel, or barred from purchasing a cup of coffee just for being of the ‘wrong’ religion (or race, or sex, or sexual orientation), and no federal, state, or local authority or law could do anything to remedy the situation.” That result would “be the antithesis of religious freedom.”

Americans United will be at the Supreme Court on Dec. 5 to show our support for Charlie, David and the LGBTQ community – and to stand up for the civil rights of everyone who could face discrimination if the justices rule the wrong way. You can learn more about our work in the Masterpiece Cakeshop case through our Protect Thy Neighbor campaign.

You can support our efforts by taking our pledge to speak out about religious freedom, fairness and equality.