I didn't want to hijack the post on the homophobic grandparents thread, so I decided to start my own to ask for some opinions. My DH thinks I'm overthinking it, and that if it is a concern to confront it later on, and that our kids will have to learn to understand that everyone has a difference of opinion on many different topics.
My parents are super religious and are very anti same-sex marriage, their religion says they accept gays, but that in order to not be sinful, gays can't act on their homosexual desires, and that SSM is unacceptable. 
We are very pro same-sex marriage and teach our children to accept everyone as they are. My DS is 10 and we lived in a state that passed SSM legislation and so we've talked about it, and he didn't understand why it needed to be a law, that everyone should just be able to marry whomever they want. He has been very curious lately about gay/bi/trans people. I've suspected that he may not be heterosexual, my guess would be bi. I don't care in any way, whatever makes him happy is good for me.
So, my mom reposts memes and other anti SSM things on facebook (we don't have any drama, there, so I'm ok with being friends, and she doesn't post often), so I know that when my son gets to the point of wanting a facebook account (thankfully this hasn't been an issue yet), that there isn't any chance that he will be allowed to be friends with any of my extended family since they are all a part of the same religion and hold the same views. I don't think that she'd actually say anything in person/skype/email about gays/SSM since she doesn't think it is an appropriate topic for children. Although the only time she really thinks it is an appropriate topic is when it is time to deny them equal rights.
So, my question is, should I start backing off and limiting contact due to this issue? I do not look forward to the day I have to tell my son that his grandmother that he loves is a flaming bigot. I wouldn't allow my kids around people that make racist comments, and she hasn't ever made bigoted comments to my kids, but I don't approve of her beliefs or opinions. I worry what will happen if one of my children end up gay and how that will play out. If one/both are gay, then I see no other option than a full CO cause I know she wouldn't be supportive, and my son would be really hurt cause he loves my mom, but even if they aren't gay, is this someone I should be allowing around my kids? My DS would be really sad not to have a relationship with my parents, and wouldn't really understand why. Or is this more of a difference of opinion like religion? He has very different opinions about religion than she does, and he seems to be ok, she's not really aware of his atheism, and I don't know if she'd be supportive of that. Do I allow him to dictate how the relationship plays out since it has already developed? Do I confront her about it? I never considered these issues when he was little since she never ever said anything about it, even though I knew her stance, but I also didn't think much about it at that point. I had set the boundary about no religious teaching of my kids, and she's been respectful of that.
What are some ways this can play out? What can I do to minimize problems and hurt feelings for my kids? Is it possible for them to maintain a relationship if he ends up gay or bi with their very different views? Am I way overthinking this, I tend to do that? Thanks. I'm a long-time lurker and have my BGP on, so let me have it.