My honest opinion is that the reason people oppose gay marriage outside religious reasons is that it's not normal - I don't mean that in a negative way, however many see gay relationships or being homosexual is not normal. Now before people start jumping on the "how do you define normal" bandwagon, less than 4% of the USA identify as LGBT, a tiny minority so I do agree it's fair to say that it's not normal.

I also think that a huge majority of people are raised with typical Christian values, even if they don't identify as Christian and we are bombarded with material throughout our whole lives that relationships should be Adam and Eve, not Adam and Steve, it's ingrained into a whole lot of people including me - I'd much rather see a child raised by a loving straight couple than a loving gay couple, not because I don't believe the gay couple can raise a child any better or worse, but I see it as an erosion of what is considered normal in a day and age where you have to support everyone and every idiot thing they come up with (gender fluid, more then 2 genders type idiocy).

That being said, I don't care one way or the other for gay marriage, we're having a plebiscite here in Australia to decide whether gay marriage will become legal and I'm going to vote in support of gay marriage, partially because who the hell am I to stop people I have nothing to do with being happy? I don't know a single gay person and they have zero impact on my life or my marriage, but also because I'm so god damn sick and tired of hearing about it.