Perhaps the trend to marrying later has something to do with it also. Married people tend to be more interested in religion, as well as tending to be more conservative in their politics.
I'm starting to feel that one of the most useless things the world ever has is opinion polls. This is from someone with engineering degree and had done university level statistics courses.
That's definitely a possibility. (I'm not married, but I think I'm one of the exceptions, as I've always been on the conservative side, politically) Age, life experiences and working in the "real world" has a lot to do with it, too. I think as people get older, they tend to "wise up" more and realize that they're not immortal and think about where they want to be in the grand scheme of things...well, at least that's what happened to me, anyway. ;)