Here's NOM on the possible discrimination case arising in Coeur d'Alene, Idaho, where a for-profit chapel, not a religious institution, has refused to marry same-sex couples in violation of the city's anti-discrimination ordinance (emphasis added):
We hope and pray that the Knapps are successful in their lawsuit. But the fact that such a lawsuit is needed at all is a sobering reminder of why we must continue to fight to roll back the damaging and unconstitutional imposition of same-sex 'marriage' that has been forced on so many States' citizens by ideologically-driven and unconscionable judges playing to a powerful special interest group.
All I've ever heard from opponents of marriage equality, including NOM, is that same-sex marriage is a question for the people to decide; there's no constitutional right to it. To support this conclusion, they point out that the Constitution says nothing about same-sex marriage. Well guess what, NOM: that means that it's not unconstitutional. What the hell in the Constitution says that same-sex marriage is prohibited? Nothing! That's what you've been saying all along to support your anti-equality stance.
Now, it's possible that they don't actually mean this, and that their inclusion of the word "unconstitutional" to describe same-sex marriage is just part of them throwing out as much negative rhetoric that they can. Still, this is a strong sign that they have no understanding of the Constitution, and that they cannot be trusted when they say that it does not protect equality.
P.S. The city of Coeur d'Alene has determined that the chapel has the legal right to discriminate, as after its owners remodeled their business to be providing only Christian-themed services, they became a "religious corporation" under the ordinance. Apparently, being for-profit doesn't disqualify a business as a "religious corporation". While I would prefer that they don't discriminate, and am not entirely convinced that a for-profit business should be a religious organization, I think that this story will have positives for our argument, as it demonstrates that same-sex marriage does not compel religious organizations to violate their beliefs.