I know it is against the values of every religion, unless you are performing ritualistic Hara Kiri, but our nation doesn't get its laws from religion, or at least it shouldn't. Look, if some schmuck wants to lose his house at a card table because he has no self-restraint, that's his business. Like prostitution, legalizing gambling would stop people from being killed because of bets. Bookies could repossess your house instead of fitting you for a pair of cement shoes. If a woman wants to have more than one husband, more power to her.
Marriage is a contract between two people.
And if the terms of their contract state that it is okay for one or both to have multiple contracts, then who cares. It just gives me shudders thinking about it. Ultimately, if you want to do anything, and it doesn't have an affect on anyone else, then do it. Sure, it might affect your family, but your family is part of your private life, and legislation should not be involved. As long as you don't beat or rape your kids or spouse, there isn't much else you can do in the home that isn't truly just a matter of individual freedom.