The National Organization for Marriage (NOM) on Monday released an ad suggesting that allowing gay couples to marry would harm society in the same way incest and pedophilia do.

In the 5-minute video posted on the group's website and YouTube channel, a female narrator says the government has 3 options to influence the behavior of its citizens.

In one example, the narrator says the government promotes police work, permits most occupations but prohibits drug dealing.

A second example includes the government promoting “natural marriage,” permitting most relationships, and prohibiting incest and pedophilia.

The government prohibits incest and pedophilia because they “harm our communities, while natural marriage benefits our communities.”

“Natural marriage,” the narrator adds, “perpetuates and stabilizes society. Everyone benefits from that, even those who don't get married. … Same-sex marriage offers no benefit for society as a whole. In fact, it hurts us.” (The video is embedded on this page. Visit our video library for more videos.)

NOM, the nation's most vociferous opponent of marriage equality, first appeared in 2007 and played a pivotal role in passage of California's gay marriage ban, Proposition 8.

The conservative group has previously called for a “civil debate” on the issue.

“We need to have a civil debate over issues like redefining marriage,” Brian Brown, president of NOM, said in a recent CNN interview in which he criticized the Southern Poverty Law Center (SPLC) for labeling the Family Research Council (FRC) a “hate group” over its anti-gay rhetoric.