Brian Brown, president of the National Organization for Marriage (NOM), this week described marriage rights for gay couples as a “profound lie” similar to slavery.

Turnout at NOM's annual March for Marriage – the first since the U.S. Supreme Court found that gay and lesbian couples have a constitutional right to marry – was low, fewer than 250 people by one count.

“Let me remind you that this is not the first time that a profound lie about who we are as human beings has been put into the law,” Brown told the crowd from behind a large sign which read, “Every child deserves a mom and a dad.”

“Slavery was one such example. The early abolitionists were told to go home. You're never going to change anything. They were mocked, derided. Even in the newspapers of the lead opinion of the day, The New York Times of the day, they were told, 'No matter what you do you're not going to change this.'”

“The civil rights movement, we witnessed the same attempt to have a lie embedded in the law and the force of government used to suppress those who might disagree with the lie,” he added.

In an interview with CNSNews, Brown vowed to continue the fight, even if it takes decades.

“It's going to take years, maybe decades, but we need a movement that has this march to be a living symbol year in and year out that we're here, we're not going away and we're growing,” Brown said.

In promoting this year's March for Marriage, NOM said that it has “an aggressive plan to fight back against the Supreme Court's profoundly unjust and unprincipled decision,” but the group has yet to provide details of the plan.