In response to: “Some (but not all) States will consider you legally married if you marry under religious law, and reside together with your spouse, even if you never get a State marriage license. It depends on whether the license is considered a mere revenue measure as opposed to being part of what renders you married.
In New York, while there is no common law marriage, if you engage in a ceremonial marriage without a license the marriage is valid, but you might have trouble proving it. However if someone marries someone else they will be subject to a bigamy prosecution and the second marriage will be void – even if they have a “get” from the first since they still need a civil divorce.