>>>>If marriage is a fundamental right as opposed to a privilege I can see this argument coming up in the future based on the 1st and 14th amendments.
>>>>
>>>>>Why don't we ever see one woman marrying many men?
>>>
>>>Marriage is a religious entity, so I can see how an athiest or agnostic might think it's okay to marry a ______________. (fill in here)
>>
>>It may have started out as a religious ceremony, but as it stands right now, "marriage" is a legally defined institution with benefits and responsibilities provided by the state. Take a gander at your marriage license if you disagree.
>>http://www.usmarriagelaws.com/search/united_states/tennessee/index.shtml
>
>If marriage doesn't have a religious underpinning, then why can't people marry multiple wives, or vice versa? The only reason is a moral reason, and last I checked, the "state" is amoral (and how).

You're assuming that only Christianity (and, in fact, only certain brands of Christianity) is a religion. Mormons are allowed more than one wife, even though most don't partake of that right, but it's there (unless they've changed the rules without telling me). Eastern religions also marry. Their marriages are based in religion, and they allow more than one wife.