Yesterday, a group of religious leaders in Virginia said that Attorney General Mark Herring should reverse his decision to not defend a challenge to a Virginia amendment banning gay marriage or face impeachment. In doing so, these so-called religious leaders made the case for legalizing gay marriage louder and more eloquently than any other group talking about the issue.
Simply this: their advocacy is an admission that the opposition to gay marriage is rooted in religious bigotry, and the State (with a capital "S," as in the Government) has no business and no interest in enforcing any religious regime, let alone one rooted in bigotry.
Allowing a religious faction to use the government--federal, state, or local--is a violation of the Establishment Clause of the United States Constitution. Anyone seeking to use government to enforce religious bigotry is violating the Constitution.
There is a whole string of case law striking down gay marriage bans on a variety of grounds like equal protection, due process, and a lack of a valid government interest--if so-called religious leaders continue to push their arguments, then we can safely add the Establishment Clause to the reasons why laws against gay marriage are unconstitutional.