Ugh, what a flawed compromise Blankenhorn and Rauch came up with. It's a good premise, that we ought to work out a compromise based on some sort of principle, but that one is wildly off the mark. It suggests that churches exist outside the law and are opposed to civil authority, when in fact most religions consider civil authority to be God-given and teach that it should be respected. And practically speaking, how can a church not recognize a same-sex marriage or civil union? Most states have laws against knowingly officiating bigamist and other civilly-invalid marriages. A priest or minister would be punished for marrying a man and a woman if the woman was officially civilly unioned to another woman at the time, so they couldn't just ignore it, they'd have to recognize it. The compromise won't work.
Their compromise led Fitz at Opine Editorials to ask the question everyone is struggling with: “Why should couples of any kind receive special treatment from the government?” Well, why? Isn't it because we should give special treatment to couples that might conceive children together? Of course it is. We never give that special treatment to couples that we forbid from conceiving together, like siblings or people already married or children. We only give it to couples that society approves of procreating together, on the condition of them affirming their consent to procreate with each other and committing to each other as procreating partners.
What do Blankenhorn and Rauch say about whether or not to allow same-sex couples to attempt to conceive together? Blankenhorn has already in his book said that marriage is, anthropologically, defined as societal approval of procreation. And, that we should only allow procreation by a man and a woman. So it's a shame he didn't suggest that as the basis of the compromise with Rauch, instead of this useless "religious exemption" that is not only irrelevant to the real issues facing us as a society in the near future, but won't work because civil law is respected by the church and the state law applies within churches. It's outrageous to suggest that churches become outlaws.
The right compromise is to recognize state civil unions that are defined as identical to marriage with the sole exception of prohibiting, rather than protecting, procreation between the couple. Churches would have to recognize them, but they certainly wouldn't recognize them as marriages, because they wouldn't civilly BE marriages. In the situation described above, where a man and woman wanted to marry but one was in a same-sex civil union, they'd have to respect the law that says that this person has entered a civil agreement not to marry anyone while they are in this civil union, just like they'd have to (and want to) respect the civil law about siblings, and about people in secular marriages that wouldn't be performed by the church, or who are already married to someone who abandoned them. Churches tell couples in those situations that they have to respect the civil law, so they have to get a civil divorce or annulment before the church can officiate their wedding, even if the church doesn't believe the existing civil marriage to be a "sacred" or "real" marriage. That's what they'd have to tell a couple where one was in a same-sex civil union. They can't ignore the legal reality, but they wouldn't be forced to recognize any same-sex marriages, because there wouldn't be any. No same-sex couple would have conception rights.
It's a much better compromise, and it should be the compromise that Congress considers, because Congress also needs to prohibit genetic engineering and same-sex conception and making a baby any way other than joining a man and a woman's unmodified gametes.
What will happen if we enact their proposed compromise, and leave same-sex conception legal? Is a church supposed to "not recognize" the very existence of people created through same-sex conception? That's ridiculous.