In this debate, no one ever asks the questions: What harm do gay people experience from being excluded from marriage? On the other hand, what harm would Congress inflict by treading all over marriage?
For example, if I'm a pig farmer, I may be offended that Jews and Muslims say my product is unclean. I may want to sue them for loss of potential profits. I could even argue they have no scientific basis. So, should I therefore have Congress redefine "kosher" and "halal" to include pork?
Could I prove that "kosher" and "halal" have caused harm to me or to society at large? Regardless, I can't sell pork to people who don't want it. Am I not attacking their religions and setting a dangerous precedent?