Marriage in America is indeed a contract — a contract that comes with more obligations than rights. Marriage in America is a civil right that is not now and has never been in the past dependent upon any one religion or even religion in general for its justification, existence, or perpetuation. Marriage exists because people desire it and the community, working through the government, helps ensure that married couples are able to do what they need to in order to survive. At no point is religion needed or even necessarily relevant.
I wholeheartedly concur that marriage is a contract, and that it is a contract with the community. That doesn’t mean, though, that marriage isn’t first and foremost a sacred rite. The confusion lies in the fact that churches were the first institutions of community in most places. The rituals that developed necessarily encompassed the entirety of the needs of the community.
The Romans were extremely secular, and their marriages generally paid only passing homage to their gods, as was their wont. The rights and responsibilities of marriage were established by the secular authorities. However, this departure was muddled by the church more or less taking over Rome (although the question of who assimilated whom is probably worthy of its own discussion).
We have reached a point in the maturity of our society when we do not need the auspices of a single (or even multiple) religious institutions in order to attend to the needs of our populace. Like it or not, people don’t need a belief in a higher power to ensure safe food preparation, prevent homicide, or rear children. Plenty of agnostics roam the earth in a state that passes for happiness, and secular humanists seem to have gotten it right.
Marriage was intended to be a sacred rite. The fact that it came to shoulder the burden of other, very necessary, civil responsibilities does not change this fact. The word itself should be relegated to a religious ceremony, and the definition of an appropriate marriage (or handfasting, for that matter) should be left entirely to the members of the religious institution. To suggest otherwise is to dishonor the varied beliefs of the vast majority of this planet.
The civil contract between a couple and the community should be the sole responsibility of the local municipal authorities. Priests and rabbis should not work for the state, at least not in this country. Let judges and mayor sign the licenses. Taking gods out of the equation in this manner might make it a little easier to allow people to have normal family lives even if they don’t happen to believe that a heterosexual union is normal for them.