...they almost always are comparing gay marriage to slavery:
Social conservative activist Ralph Reed drew an interesting parallel over the weekend while encouraging same-sex marriage opponents: Gay marriage has largely been imposed by the courts over the past year, much like the Dred Scott decision, he said. Abolitionists didn't give up then, he argued, and we can't now.... "Anybody heard lately that we’re losing the marriage issue? Anybody heard that argument? You notice some similarities?" he continued. "I’m not comparing slavery to same-sex marriage, OK? I’m just pointing out that when you have these fights, what’s interesting is that if you look at same-sex marriage, it’s now legal in 17 states. Only six of them, six out of those 17, six out of 50 states, had done it by referendum or by state legislature. In every other case, it was imposed by courts. Just like the courts had to impose Dred Scott. Because they couldn’t do it on the country because the country didn’t agree with it. The country, by the way, doesn’t agree with same-sex marriage," Reed concluded.
I'm not so sure "the country" didn't agree with the Dred Scott decision. I'm also not aware of any polling on the 1857 decision... but I'm guessing a majority of Americans would've agreed with the court when it ruled "that African Americans, whether slave or free, could not be American citizens and therefore had no standing to sue in federal court." Reed's suggestion here—that Dred Scott ruling was "imposed" on the country by unaccountable judges or whatever—is historical whitewashing at its most literal.
The much more salient case is Loving v. Virginia, the 1967 Supreme Court ruling that "imposed" interracial marriage on twelve states. Polling data on interracial marriage does exist from 1967 and at that time more than 70% of Americans opposed it. If they put interracial marriage on the ballot in 1967, Americans would've voted against it. They would've crushed it. So if Reed thinks it's wrong for the courts to "impose" same-sex marriage on the country because the "country doesn't agree with it"—if Reed thinks its wrong for justices to conclude that the LGBT people are covered by, say, the equal protections clause, just as all other citizens are—then Reed must believe that Loving was wrongly decided as well.
Point this out to bigots like Reed and they slap this Get Out of Logical Consistency Free Card on the table: Loving is totally different because that case was about opposite-sex couples and opposite-sexers can make babies and same-sexers can't and the lack of popular support—which is all we need to know about same-sex marriage—is completely irrelevant in the case of interracial marriages BECAUSE BAYBEEZ.
Reed shouldn't be allowed to get away with this slight of hand/insult to your intelligence. He also shouldn't be allowed to get away with claiming that the country "doesn't agree" with same-sex marriage. (It's not 2004 anymore, Ralph.) A large and growing majority of Americans does agree with same-sex marriage and, more troubling for Reed, a majority of those who disagree with same-sex marriage aren't willing to do anything to stop it. Read the polls, Ralph. It's all there, black and white, clear as crystal.