Old and young, gay and straight, marriage defense advocates rallied outside the Supreme Court in Washington, D.C. on Tuesday, calling for the institution of marriage to be maintained.

Doug Mainwaring was one of those standing up in defense of marriage as the union of a man and woman.

He himself is an admitted former member of a same-sex union.

"I have as much trouble with no-fault divorce as I have with same-sex marriage," he told an audience outside the Court building.

Nonetheless, he sees danger in re-defining marriage – so much so that he is actively fighting it in front of the Supreme Court.

"The way I got into this was through concern for my children," he explained to CNA. "In trying to form a family with another man, I finally concluded this is nuts. My kids don't need two dads in the house. They need both a mother and a father."

He left the union to repair his marriage, which he believes was in the best interest of his children.

"Kids don't have a voice," he said of the current marriage debate. "I know many who were raised in same-sex households who even though they love their parents, they deeply, deeply regret that parent of the other gender that they missed having a relationship with. And I just believe we need to do whatever's best for children."

Mainwaring was among the crowds who stood outside the Supreme Court as it heard oral arguments April 28 in Obergefell v. Hodges, a case appealed to the nation's highest court from the Sixth Circuit Court of Appeals.

The case deals with same-sex couples' lawsuits against four states – Michigan, Ohio, Kentucky, and Tennessee – over laws defining marriage as between a man and a woman. The Sixth Circuit previously upheld the laws, saying that the states had the power to define marriage.

The Supreme Court agreed to hear the cases in January, to decide under the 14th Amendment if states must grant marriage licenses to same-sex couples and recognize same-sex marriages conducted in other states. The case could result in a nationwide redefinition of marriage. The Court will likely issue a ruling in June.

Outside the Court on Tuesday morning, activists on both sides of the marriage issue packed the sidewalks.

Andrew Guernsey, a junior at Johns Hopkins University, was frank about his fellow Millennials who support same-sex marriage.

"I think many of my peers are misguided on the issue," he said.

While many young people believe they are "fighting for equality," he explained, "(w)hat they're asking for is changing what marriage is."

"And we can love our gay and lesbian friends without changing the fact that every child comes from a mom and a dad. And there's something special about that."

Caitlin La Ruffa, director of the Love and Fidelity Network, agreed. Her organization works to help educate and prepare young people to support and defend marriage.

She said that her generation has already been stung by changes to marriage, such as no-fault divorce. To re-define marriage further will only make things worse, she maintained.

"They've seen the breakdown, and their families have been devastated by it," she said of Millennials, noting that many young people have not been raised by both a mother and a father.

"Most of us aren't parents yet," she added, continuing to say that she thinks more young people might support marriage as the union of man and woman as they themselves get married.

Ryan Bomberger, co-founder of the pro-life Radiance Foundation, also spoke in defense of marriage.

"None of this has to do with equality," said of the push for same-sex marriage. "It has to do with others' ideology being forced upon us and for us to accept it."

As a black man, as well as "someone who was adopted and grew up in a very diverse home, someone born as a result of rape, I know all about equality," he said.

Bomberger said that he sees marriage as a "foundational issue of any society" and "a core conviction that can't be changed by any poll or any Supreme Court ruling."

While supporters of same-sex marriage flock to the 14th Amendment to argue in favor of a right to marriage that cannot be infringed upon, Bomberger says that there is no right to same-sex marriage there.

The amendment, adopted three years after the end of the Civil War, "was actually to ascribe humanity to people of my complexion," he said of the amendment, which solidified due process rights for freed slaves in the South. "It was not to affirm every single behavior known to humankind."

Ultimately, the argument to defend marriage is about love and not judgment, Bomberger maintained. However, this view often gets attacked, he said, by a society that does not understand the true definition of love.

"We've lost the concept of what love is," he insisted, noting that as a father, he "will warn" his children out of love "against actions and behaviors that are destructive to them."

"Because I love them," he stressed, "I try to keep them from doing it."