I'm going to offer a new perspective here on this whole "church and state" that seems to be popping up.
America has a democracy (for the sake of staying on topic, let's just suppose this is true) or a democratic republic, but the point is the same
A democracy is defined as citizens determining the public policy of their own nation: a majority will win
If the majority happens to be religious, then why is it not within the limits of the US Constitution to impliment religious social policy? That's the democratic thing to do.
For example, I'm sure Thorne here would be all about pro-choice, and would say that a minority of right-wing religious fundamentalists are out to restrict the proceedure, but if we go by a recent poll, where 59% of americans identify as pro-life, then they should get to determine the public policy that says "no abortions"