Matthew J. Franck from Bench Memos at NRO offers insight to the much misunderstood topic of separation of Church and State and the so-called "legislating morality" issue. The case under discussion is the one being brought by David Boies and Ted Olsen to overturn California's Proposition 8 (now a CA state constitution amendment) which enshrines in law marriage between one man and one woman. Here is the excerpt that exposes the fallacy of needing to segregate religiously informed arguments out of the public square when considering legislating any law. His comments below have another case in mind as the reference point.
Because of the diversity of religious commitments in our society—and because it violates our constitutional morality, and no little part of our dominant religious morality, for anyone to be coerced in matters of faith and practice—we must express our moral opinions to one another in a shared language of reasons and arguments. This does not and cannot mean that the connection of our moral arguments to our religious sentiments is severed when we meet in the public square. But when all the arguments have been aired out, the moral view that prevails at the ballot box and in the legislative halls is entitled to have its way in public policy, barring any explicit constitutional obstacles to its enactment. The “separation of church and state” is not one of those obstacles. If it were, no law with any moral purpose that happened to coincide with the view of any religious community could ever be upheld.
All of this escapes the Iowa justices, whose view seems to be that if a moral argument finds support in any religious commitment, then the promulgation of that argument in law is a violation of the principle of religious disestablishment. This is logically fallacious, historically illiterate, and politically brutish.
The whole thing is worth reading...