So we are all on the same page:
Judeo-Christian Ethic: nothing to do with the founding of the nation. It is a term invented a little over 100 years ago to curry favor with the wealthy Jewish communities and to make Christians feel good perhaps. There literally is no such thing and it has no roots in 18th century colonial life.
Constitution: makes no mention of marriage whatsoever. None.
Judicial Activism: Basically in the absence of law, judges decide. There is a separation in a federal law and state laws and what is guaranteed and decidable in federal courts and what are topics reserved for state courts. These are not "one thing".
Founding Fathers/bible: One either believes that homosexuality is a "born as" or "acquired" taste. There is no evidence whatsoever that it is taught or acquired. But to the point, the founding fathers were just plain folks and not Divine. They kept the bible out of things. Purposefully. We are NOT founded by people who thought that the bible was the rule of law. Just the opposite.
Half the states permit marrying your cousin. For a long time in the 20s and 30s, people of various ethnic backgrounds and intelligence were not permitted to marry anyway. Blacks weren't permitted to marry whites for a significant period. Ugh.
Last, marriage is church sanctioned civil unions. Ministers are extended the courtesy by the state to perform civil unions and as they occur in places of worship, they are "sanctified" and called marriages. Is that clear?
What we have now are two forms of the marriage/civil union contract and it is a contract that the states govern. One that has all rights and benefits and another that doesn't. How can that be? We are equal under God (so we are told), the Constitution prohibits the rights of one over another, and there is no ethic or tradition that trumps law.
Clear?