I genuinely feel sorry for those that do not even realise that their objections really come down to homophobia. The main objection is basically a semantic argument over the word 'marriage.' In reality many of them think that this will somehow lead to more homosexuals which they don't want.
It is often religious people that are so against gay marriage which some people think makes it OK. However, when you see how clear Jesus was about the issue of divorce and how little they campaign about that, this argument falls apart. The majority of Christians in this country are in churches which allow divorce. What exactly is it about this specific issue of marriage that they take such a firm stance against?
It's like they suspend their logic when it comes to this issue. On Question Time there was a woman from Christian Voices who started on about how their voice has been ignored despite a petition of 600k people. Firstly, they would only be classed as having listened to them if they gave in to them and secondly that amount of people isn't even 2% of the population.