There is one anti-gay-marriage demographic, however, that must be viewed a little differently, and that's African-Americans. For many of them, the reasons of ignorance, fear and faith apply, but there's another component that's not hard to understand. Black Americans are still recovering from hundreds of years (beginning pre-Slavery) of being deeply oppressed and barely regarded as human. They see this history as a prime reason that so many black men (past and present) have been socially emasculated. They don't want to trade "nigger" for "faggot" as the newest slur to overcome. And there's already considerable resentment that a significant proportion of black men reject black women in favor of women of other races. For blacks, gay marriage feels threatening to their continued existence and growth as a community stabilized by solid traditional marriages and strong families. This is not an unreasonable concern, but, blacks will nonetheless have to struggle with this important social change along with everyone else.
In the larger, over-all sense, gay marriage is abhorrent to many in the same way that racial civil rights and women’s rights went against much of the American grain – because they signaled significant change in how America would look and function. There’s also the matter of a prevalent human instinct to feel superior to someone, and since it’s become “politically incorrect” to feel superior to women (although that’s sure making a comeback) and blacks (although that’s nowhere near over), gays and illegal aliens now bear the brunt. Hispanics and Asians can’t escape the hate-mobile either, but the “immorals” and the “illegals” are much more acceptable targets – essentially in the same category as terrorists.