Sort of the problem is that the "religious right" is that it is a rather homogenous block compared to left-wingers. On a great range of issues, it's easier to erode support by liberals/Democrats than conservatives/Republicans because they are more inclined to make decisions themselves (sometimes carelessly) rather than submissively obey the establishment. With that in mind, two things need to happen:
Those who seek progressive ends for themselves need to respect that there are other people seeking other progressive ends for themselves, and they can't stand for getting rights for themselves but still allowing the others (particularly those facing a similar plight) to get trampled on. It's selfish to give in to a divide-and-conquer strategy.
Still, there is the flip side... we have to erode the seemingly unbreakable block of people who have such a great deal of ignorance about social issues (including GLBTI). I don't think we go for a direct assault, but we can deal with what holds them together -- a submissive ignorance that keeps them from thinking and making decisions for themselves. We have nudge people to stray from their comfort zone and challenge all the ideas they are exposed to. To use (in)deductive reasoning to test ideas, preferably with multiple philosophies. And above all, not just take directions from someone else on how and what to think.