I was glad to have a straight friend tell me about this encounter with a pastor-type... The pastor was of the type that it's a sin, but one shouldn't judge, etc. But he didn't think two men should be married. My friend asked, "But would you marry two fat people?"
Since the pastor was of the type of "not judging" (cough*yeahright*cough) that at least got him thinking. Sadly those that really pick and choose have all the reasons for why it is still a sin and eating shellfish isn't still a sin all rehearsed, and you can't win with those types of people - those ones it's better to walk away from. But if someone is truly open-minded, sometimes the other comparisons can work.
Of course, what my friend used isn't a true comparison as - with a few possible medical conditions aside - a person that is fat could lose weight, whereas I could NOT be straight. (Hence the popular videos "Did you choose to be straight?" I've seen on youtube and such).
Exposure and time help. When my sisters first found out, and thought it was perhaps the result of upbringing, they said, "What did we do wrong?". When I mentioned that having a gay uncle it might be genetic, they said with a look of fear in their eyes: "Does that mean our kids might be gay?" There was no winning. A few years later, and I'm not entirely sure what prompted it to this day, my younger sister started crying about how it wasn't fair to kids if their parents chose to be gay. I had not talked about having kids since when I thought I was straight, and really didn't know how to handle that one.
But shows/movies are helping (shh, don't let 1 Mil'n Moms know that, even abbreviating in case they google themselves), and once my older sister called me after seeing "Prayers for Bobby" and apologized to me, saying she hadn't realized how hard it could be for me.
I'm going way off subject here... but if they're close, just be you, let them realize it on their own... if they're not, ask them if they're also sick of the agenda of the disabled and if that group, also discriminated against in the Bible, should be allowed rights.
The truly obsessed against gays will have their answer ready and should not be bothered with. The others will realize they don't know the Bible like they think they do.
Leviticus 2118 No man who has any defect may come near: no man who is blind or lame, disfigured or deformed; 19 no man with a crippled foot or hand, 20 or who is hunchbacked or dwarfed, or who has any eye defect, or who has festering or running sores or damaged testicles. 21 No descendant of Aaron the priest who has any defect is to come near to present the offerings made to the LORD by fire. He has a defect; he must not come near to offer the food of his God