Marriage, not to be confused with Holy Matrimony, is a legal contract requiring a license issued by the state. As such, it is inherently unconstitutional to deny same-sex couples the right to enter into such a contract that is afforded every other consenting couple of legal age.
If you’re a Citizen, You’ll leave Out Your Religious Beliefs Out of Your Opposition to Same Sex Marriage
It’s much more expedient to have this discussion reminding people that the United States is a secular republic because the Constitution is much clearer about the the matter than The Bible.
Most court cases challenging prohibitions against same sex marriage are based on those prohibitions being violations of the 14th Amendment. I take another tact and focus on the etiology of that opposition being a violation The Establishment Clause of the First Amendment. There is very little coherence, if any, in an argument in opposition to same sex marriage that isn’t based on a theology, faulty or otherwise.
Bigots who oppose same sex marriage forget that that outside of their church, beyond the intended sight of God, that marriage is a contract between two consenting adults. To insist and codify that people Here be obliged to marry as part of a religious act is theocracy - in opposition and defiance of the rules written down in the Constitution.