Beneath the surface of the movement for same-sex marriage is a deeper claim, which is really about etching in tablets of law the assertion that heterosexuality and homosexuality are essentially the same. Should the law choose to recognize this claim, homosexuality will stand in our culture as the functional equivalent of heterosexuality, and all attendant cultural adjustments must follow. This is the equality that is sought.
Furthermore, despite prevailing opinion, marriage isn't a right to be exercised by two individuals. It is a social contract that involves the spouses, their offspring and the state. The state steps in to validate marriage - and to confer certain benefits - precisely because the state has an interest in the well-being of the next generation that the marriage relationship naturally produces.
It's a peculiar moment in human history when one is forced to make a case for Nature, but such has been the success of the same-sex marriage movement. By cloaking their arguments in a veil of civil rights, advocates have created an atmosphere in which defenders of traditional marriage are automatically defined as bigots. I remember when a "bigot" was someone who hated and condemned a person; now it is being recast to condemn those offering a good-faith argument in the public square.
That men and women were intended to bond sexually and that this heterosexual love has the capacity to bestow human life is irrefutable. It also follows that society has an interest in supporting marriage for the careful rearing of children. That children need, deserve and have a right to both a mother and a father - even if fate and human failing prevents it - seems a goal worthy of protection.
At the same time, let the case be made for civil unions that satisfy the legal concerns of same-sex families. But the current wish by some to equate heterosexual and homosexual unions is an emotional plea posing as a civil rights statement. Hijacking the moral authority of the civil-rights movement in order to demand equality of heterosexual and homosexual unions is a piece of sophistry that does no service to the next generation.