There's been a lot of speculation that the reason is money. Gobs and gobs of money. Scaring people about the eeeevil gays attaining a marriage of equality is lucrative, if you scare the right people. Brian Brown, the head honcho at the (badly named) National Organization for Marriage makes six figures annually. NOM was a couple million in the red last year, but Brown got paid. Still, with the massive success of the marriage equality movement over the last couple of years, another mystery is what they'll all do once the anti-gay money train runs off the tracks?
Shift gears! Exploit another aspect of your tangled web of religion and politics! Well, I don't know if that's what NOM will do, or its affiliates and "family"-named compatriots. But here's just one example, one of the smaller groups populating Facebook is changing its name from "I Support Traditional Marriage," to the much more dramatic (and nonetheless vague) "Warriors for Christ." Their new motto is, "We will not keep silent." Because free speech, of course, and I've gotta wonder who they imagine has been silencing them. Maybe that's the new angle: paranoia over "persecution" of Christians? I'd bet on it.
By the way, if you think this is trivial because of the small number of followers this page had, I agree. But keep in mind, though NOM does fairly well on Facebook with 39K followers, their Twitter followers are logging about 7,000. How many of them are people like me, keeping tabs on them would be speculation, but I speculate: half. And even if every one was legit, that's a fairly paltry number of followers for a movement. For contrast, The Rachel Maddow Show has 1.1 million Facebook likes, and 2.8 million Twitter followers.