While the idea is for people to become married and have offspring not all such couples produce, and while some would argue that this denegrates the idea of marriage there is no practical way to determine if such an outcome is going to occur. Over time it is accepted that some will no add to the population and hence the future of the country but such does not detract from the general idea that they, being man and woman, can create such life.
Re-defining this role of marriage to be inclusive to man-man, woman-woman, destroys the intent and definition of what marriage is to society. No one is stopping people from living with whom they choose, but by giving tax breaks and such to those, in marriage, can add to society puts a burden of taxation on the whole for the desire of those who wish to give nothing back to said society.
Civil unions may well, in fact, be a good idea for those gay and those who are not gay who wish to share a life where they do not wish to pro-create or cannot. Marriage from a general stand point revolves around the committment of two people who wish take on the burden (and joys) of raising children, whereas those not wanting to do so have more time and money to spend on themselves alone. Watering down marriage to something as simple as sex takes away from the intent of it.
Not all marriages work, are perfect, or produce children. In a world of marital dissaray (or so it sometimes seems) redefining marriage to be solely about two people without the capacity to create weakens the institution further for the selfish desires of those who simply want to legitimize their desires to have something which was never intended.
Marriage is an idea with a purpose, it is a creation of a time tested and proven idea. Marriage of a man and a woman has a potential for greater benefit to all, gay marriage does not. It is not a freedom issue, it a financial one - we give benefits to those who marry which come from our hard earned income because we believe it benefits us in the long run - we invest in it. Investing in something which will never produce is a losing proposition, investing in something that usually does produce, but not always, is more prudent.
Etc, blah, blah, blah.
While the idea is for people to become married and have offspring not all such couples produce, and while some would argue that this denegrates the idea of marriage there is no practical way to determine if such an outcome is going to occur. Over time it is accepted that some will no add to the population and hence the future of the country but such does not detract from the general idea that they, being man and woman, can create such life.Ah, but I'm sure the raw number of hetero couples who marry without any desire to ever raise children will always be higher than the numbers of gays who want to marry, children or no.
Anyway, I disagree that we can't police childless marriages: Make the marriage license a conditional contract. If, after 4 years, the married couple hasn't produced or adopted a child, then their marriage is voided. Plus they have to pay back any benefits they had received from their marriage.
We can play with the initial grace period, and there are many ways to structure enforcement so that a childless married couple still have options after the grace period ends. No need to be draconian about it. But the essential framework should be quite enforceable.
I'm not sure that I would oppose such a framework, but I doubt very much if you could ever get such a law passed in America. But to anyone who wouldn't stand for such a system that required a married couple to actually produce children like they implicitly promised to do when they married, then it's hard to see how they could turn around and oppose gay marriage.