The National Organization for Marriage (NOM) has equated opposing gay marriage to opposing slavery.

In a fundraising campaign highlighting Brendan Eich's decision to step down as CEO of Mozilla over his 2008 donation in support of Proposition 8, an amendment to the California Constitution which for over 4 years excluded gay couples from marriage, NOM asserts that abolitionists faced similar attacks for their beliefs.

(Related: Brendan Eich steps down as Mozilla CEO over past support for Proposition 8.)

“Scholars, public figures, and average citizens who publically defend the institution of marriage as the conjugal union of one man and one woman often face character assassination and occasionally threats of physical violence. Facing similarly vicious attacks in the decades leading up to the Civil War, America's abolitionists recalled the timeless insight that 'Eternal vigilance is the price of liberty.' The wisdom of these words applies as much today as then. If the calculated use of fear and intimidation is permitted to dominate this important public debate, America will lose not just the time-tested institution of marriage but also endanger our form of government which depends on the free and open exchange of ideas.”

Leaked documents in 2012 revealed a NOM strategy to “drive a wedge between gays and blacks.”

Writing at ThinkProgress.com, Zack Ford noted that the campaign, titled Keep The Republic & Marriage, is the “latest use of an explicit tactic to portray LGBT advocates as anti-conservative oppressors.”