Well, we've covered the "gay rights" and "gay marriage" discussions in detail on the two threads by that name...within which the points of the -lack- of separation of church and state have surfaced.
But this thread focuses primarily on the latter, so I'll have at it: AFAIK, separation of church and state was constitutionally ideal, but historically speaking this is impossible- the laws were founded on the religious axiologies that the people who made them were born and raised on. Hence the morality that the law reflected could be arguably religiously motivated.
But even this doesn't necessarily mean that religion and the state are linked- since the principles behind the morality that the religion underpins are not exclusive (it would be pretty darn problematic if they were: "No, YOUR religion can't disapprove of murder because MY religion does!"), even if traditional interpretations of some religions entail that the religions ARE exclusive.
The main problem here is that more recently, it seems, there has been a resurgence of religion, especially since 9/11. Question is, is this an absolute revival, is it relative and subject to media focus, is it a small bunch of fundamentalists using loudspeakers, or is the fundamentalist population growing, or what?
Regardless of what it might or mightn't be, it has to be said that the net effect is apparent: religion and its surrounding issues are, in a meaningful way, being placed on the map very clearly, since we're all discussing them now. And so whilst the age of secular humanism might still prevail in some limited ways, the religious motivations for political decisions are increasing in incidence and most importantly visibility. Most recently, everybody has finally noticed the way it has taken a concrete hold of politics itself.
I would say that this is a slightly separate concern from the point about historical roots I raised earlier- because I think the recent manifestation is more a social phenomena than, say...part of a cornerstone feature of the society it takes part in.