WASHINGTON -- Emotions flew high Tuesday at the U.S. Supreme Court, where the justices took up the challenge to Proposition 8, California's 2008 voter-approved ballot measure that defines marriage as between a man and a woman.
After 80 minutes of oral arguments - some even questioning whether the case should be judged by this court - attorneys on both sides sounded conservatively optimistic.
"We don't know for sure what the United States Supreme Court is going to do, but we're very, very gratified that they listened," Ted Olson, attorney against Prop 8, said.
"A victory here for us means that this issue returns to the people and their legislatures and their elected representatives where the debate belongs," Andrew Pugno, with Protect Marriage Coalition, said.
But the tone outside the court was more resounding. Early this morning, activists met on the National Mall to march in support of traditional marriage.
"It's important to me and it's important to my children that the definition of marriage remains between one man and one woman," traditional marriage supporter Kathleen Abela said.
Old and young, they carried signs and walked hand-in-hand to the Supreme Court, where they clashed with protestors rallying for same-sex marriage.
"One woman, one man, no hate - we're just disagreeing," one traditional marriage supporter said.
Robert, a Maryland resident who favors Prop 8, said the scene at the Supreme Court reduced him to tears.
"I want to personally repent for everything I've done to bring this on to this country," he said. "If we do not repent of our sins, we will not recover. America will not recover."
Meanwhile, supporters of same-sex marriage rallied and chanted for marriage equality.
Speakers like the Rev. Gene Robinson, the Episcopal Church's first openly gay bishop, told CBN News the fight is really about love.
"At the end of the day, God is love. Look at our relationships. Look at our families and tell us if you don't see love there. And if love is there, then God is there," he said.
Jim Garlow, with California's Skyline Church, is one of the California pastors that pushed Proposition 8 to the ballot. He said the fight over marriage is about expanding a liberal agenda.
"There isn't that much interest in commitment, monogamy," he told CBN News. "It isn't there. It's attempting to force us to affirm a lifestyle. That's what's at stake here."
Polls show most Americans now approve of same-sex marriage, with younger people supporting it and older people opposing it.
"So we see strong divisions among older Democrats and older Republicans," Dan Cox, research director of the Public Religion Research Institute, said. "But when we look at millenials, that's Americans under the age of 30, we actually see the partisan differences diminishing."
Still, some conservatives like the Heritage Foundation's Ryan Anderson, co-author of the book What Is Marriage?, are trying to turn the tide of public opinion. He worries changing its definition would only make the decades-long decline worse.
"Same-sex attracted Americans are not to blame for the problem that we face in America right now," he told CBN News. "But the question we have to ask is do we want to double down on the mistakes of the last 40 years? Or do we want to start recovering a more sound understanding of what marriage is and why it matters?"
Anderson and others worry that legalizing same-sex marriage could have serious consequences.
For one, it could be the first step to redefining marriage altogether, possibly leading to polygamy or even group marriages with multiple partners. Some advocates of gay marriage openly support those ideas.
Also, same-sex marriage could eventually hurt religious freedom in America because churches, religious organizations, and even businesses will have to support whatever the government defines as a marriage or possibly face government action.
But Anderson believes there's hope for supporters of traditional marriage. Just as the pro-life movement made its case for years and changed public opinion, leading to state laws limiting abortions, Anderson believes supporters of traditional marriage can do the same.
So as young people grow up, they will understand the value of the traditional family and change their views.
"Forty years later, my generation is now more pro-life than my parents' generation," Anderson said. "And the same thing is true for marriage. We're just starting this discussion about marriage."
Meanwhile, for Bishop Robinson's daughter, opening the door to marriage equality for her dad and his partner would make the institution stronger for everyone.
"That love is as deserving and as important as a love for straight parents," Ella Robinson said. "There's a lot of love in the air here, and I couldn't be more proud to be here with my dad, and so it's really exciting."
A ruling on the case is not expected until later this year.