At a rally held Tuesday at the Utah Capitol, Brian Brown, president of the National Organization for Marriage (NOM), called on opponents of gay marriage to “stand up and be a hero.”

The rally comes roughly a month after a federal judge declared invalid Amendment 3, Utah's 2004 voter-approved constitutional amendment limiting marriage to heterosexual couples. For 17 days before the Supreme Court granted a stay in the ruling, Utah was the 18th state to legalize same-sex marriage. During that time, more than 1,300 gay couples exchanged vows.

According to the AP, roughly 700 people attended the evening rally, where organizers handed out signs which read “Biology is not bigotry” and “Marriage means a mother and a father for every child.”

Brown compared his group's fight to exclude gay couples from marriage to the slave trade, saying that people of faith throughout history have led in the fight for “true civil rights.”

“Throughout history people of faith have stood up against gross injustices. Stood up for true civil rights,” Brown said.

“People of faith came together and said, 'There is something profoundly wrong with an empire that is trading in the flesh of human beings. We will organize. We will fight.' They were laughed at. They were mocked.”

Brown called on those in the crowd to “stand up and be a hero.”

Republican Utah Attorney General Sean Reyes, who is leading the state's appeal in the case, received a standing ovation when he told the crowd that he does “not believe this is a losing case.”

Doug Mainwaring, an openly gay tea party activist, also addressed the crowd, saying that “it is not homophobic to oppose same-sex marriage” because “kids need and learn from both a mom and a dad and they deserve to have them.”

The event took place a few hours after roughly 300 marriage equality supporters rallied at the Capitol steps.

“Marriage is the foundation of society,” said Mark Lawrence, director of the group Restore Our Humanity. “Yes, we agree with that. And that foundation will only be strengthened when it's built upon equality, decency and humanity.”