katisara:
Did any churches have an explicit ban (regardless of the bible)? Or was it strictly at the local level?
Do you mean organized denominations? I don't know if the Southern Baptist conference had any explicit planks or not, but they did issue a Resolution in 1995, clearly apologizing for their part in perpetuating racism. Jerry Falwell also made a number of public statements against interracial marriage in the 50's.
For the most part, they didn't need an explicit ban, since interracial unions were against the law in many states. They remained illegal until 67, I think, when the Supreme Court declared such laws unconstitutional. (And even then, it took a while for them to be removed; Alabama was the last state to take the laws off the books, and that was in 2000.)
However, doing my research, I stumbled across a few interesting facts. It's been about 45 years since the ruling. Ever since then, the number of people who disapprove has gone down every year. In the 80's, the numbers were about 50-50; nowadays it's almost at 90% approval (although some pairings are more approved of than others).
So, if gay marriage follows the same path as interracial marriage, the first step is that a lot of states will start allowing it. Many state Supreme Courts were striking down anti-miscegeny laws before 1967. As time progresses, people will change their minds and start becoming more accepting; and churches will follow suit. Even Jerry Falwell, before he died, made a lot of statements trying to reach out the LGBT communities.