I don't think the Sesame characters need to explore gays or religion on their program due to the target age group.
I can see them having these people but not making it an issue. I mean, I'm not old enough to have seen pre-1977, but did SST go out of its way to do whole episodes on "this person is black, this person is brown", etc? There were just different types of folks living there and we were just supposed to go with it.
When Dinosaurs addressed religion, it was definitely overt, though obviously no actual religions could be named as they technically hadn't been invented yet, LOL.
My favorite religion analogue will always remain the FR episode where different Fraggle factions are generated based on some stupid radio commercials. The message was subtle and would go over the heads of the youngest viewers.
I think that, sometimes, making a big deal out of an issue MAKES it a big deal. I've never been one to engage in ostentatious sign-waving/chanting/whatever. I just form a conclusion and act accordingly. I remember reading a review for Finding Nemo, where Nemo's physical difference was treated as a non-issue (technically, that was true for everyone aside from the father, but whatever
). I think that, regardless of whatever social issues we face today, perhaps the best idea is to just treat it as "whatever" instead of "OMG RECORD THIS AND DESIGN A DISSCUSION GROUP AROUND IT".