Before you get up in arms and think that I am trying to argue that legalizing gay marriage will lead to a slippery slope (polygamy, people marrying animals or kids, etc...), that is not my point. I am not trying to argue against gay marriage. I really want to get a sampling of opinions. Should polygamy be illegal? If not, why? If so, why?

For a little devil's advocacy and to get your hearts appropriately bleeding, let's say a loving muslim family (I almost said couple, then I almost said threesome hehe) of one man and his two wives comes from Saudi Arabia to live in the US. Only they find that they cannot remain legally married here due to our anti-polygamy laws, and to their horror at least one of the loving soul mates must leave the marriage. All three are devastated. Assume they wouldn't be prohibited from entering the US in the first place.

And please don't say it should be illegal because the supreme court has already ruled on it. If laws banning gay marriage had come before SCOTUS like polygamy did in the 1800s they would have upheld those too.

The reason this question is not directed to opponents of gay marriage is because I think I already know what they all would say anyway.