I consider myself a fairly orthodox Catholic – though not conservative. I support and accept the Churches teaching & understanding on marriage.
That being said, I have no clue why there should be an opposition to gay marriage in this country. I don’t deny that this is wrong – I consider it wrong. However the way this country was set up esp. its incorporation of mechanized morality, I have no clue why either gay marriage or polygamy or anything else should be illegal if it does not harm anyone else.
It harms the people involved, and by extension, harms others. Same-sex acts, especially among males, are inherently damaging to the body. I don't know how graphically detailed I'm allowed to get on the forum here, but let's just say that it can be damaging on both "active" and "passive" partners. Disease spreads more easily because it involves direct access to the digestive tract. This is why sexually active, polyamorous, homosexual males tend to fall prey to STDs more frequently than others. But even in a monogamous relationship, it's physically damaging.
Polgamy (multiple marriages) or polyamory (having multiple lovers, married or otherwise) are damaging to the sexual economy in general. Hey, if all the ridiculously good-looking men had three wives, what would the other two-thirds of straight men do? Ugh. A mismatch of available males and available females leads to serious social unrest -- this is what China is going to have to deal with as a result of aborting girls so much.
If people do not reproduce at a stable rate, the economy will be put in jeopardy. If there is not an average of 2.1 births per woman, we can't maintain the current economic system. California is liberal enough to not reproduce adequately. And guess what? That means there are going to be more old people and not enough workers. Which means there's gonna be more retired folk on Social Security but a smaller pool of workers to tax for Social Security. Which means there will be more taxes per worker. Which means workers make less. Which means they spend less. And workers not spending, for the economy, is like a heart not beating. All this because of a lack of stable population growth or even keeping the current population or shrinking slowly.
We can thank the contraceptive mentality for this, but this is why sexual activity should remain open to procreation. Otherwise, society falls apart with regard to health, morals, and the economy.
And all this is completely apart from the legal problem with so-called gay "marriage". No persons are being discriminated against by not passing gay marriage. A straight guy and a gay guy are both equally capable of marrying a woman, and both are equally restricted from marrying other men. As individuals, nobody is being discriminated against. However, the question is: are all couples or relationships equal? Relationships are not persons before the law, and thus do not have the benefit of the 14th amendment.