I haven't said any societies would fall apart or implode. I don't think that.
But it is a concern among some denominations. No one said they would have to, but many churches have become litigation shy. I've read Tammy Bruce (and I know a lot of people disagree with her, and she's been called a "traitor", etc) among other commentators discuss this possibility- because people with a political axe to grind have done similar things before. Don't know if it would happen, just saying it's a concern I've heard expressed among people in more conservative churches including the Catholic church. Maybe it's a slippery slope argument, but I think it's a genuine worry people have, that their churches will be legally attacked if they defend their doctrines.
To answer your example directly, the Catholic church isn't pressed to marry Jewish couples, because Jewish couples don't ask to be married in the church. They have no reason to. If a gay couple did, and they were refused, you don't think there are advocacy groups who would undertake a lawsuit or campaign against the Catholic church? Just asking- because this is the fear people have based on past political actions. No matter if you agree with it, there are Christians and Catholics who truly believe their faith is under attack, and people are looking for any and all ways to get them. Again- I'm not saying this, but this is their belief based on personal experience and the sort of litigation they see coming into courts recently.
Thanks for the food for thought. I'll pass it on in my discussions with church people. As I said, I'm in favor of gay marriage. Marriage is ultimately a legal contract, and we really should sever it from the religious dimension. If you want words said over your union by a religious authority, fine, but a judge or other government official should have to sign that license. On the other hand, I've had Libertarians tell me that the state should have nothing to do with marriage because the state has no abiding interest in it.
Sorry for the wordy reply (can you tell I used to be an historian in my pre-mother life?). I just wanted to be give a thorough answer so as not to be misunderstood, being a guest and all.
Julie