The differences aren't "slight" that's why.
And for someone who are argued that we should adopt a simple solution to then argue that "heterosexual marriage" should replace "marriage".
This is misrepresenting what I said. I'm not saying that we should always call marriage 'heterosexual marriage.' However, the terms 'heterosexual relationships' and 'homosexual relationships,' are used as a descriptor without feeling the need for a different word for relationship. The differences between the two in this case are also more than slight.
Two people entering into a contract to make a lifelong commitment to each other should, in my opinion, be called a marriage. It depends on your perspective whether you class the gender of the two people as making a huge difference.
I think it's easily explained. They believe that the Sky Pixie created marriage between man and woman and that by allowing man to marry man or woman to marry woman, they would be in violation of God's will.
Merely allowing homosexuals to live without being stoned to death or pestered in any way is not a violation of God's will since the Sky Pixie told them to love thy neighbour and to love the sinner.
Do they honestly believe that God is OK with two men entering a civil-partnership with all the rights of a marriage but he is dead set against this being called a marriage. I never had God down as a pedant.
There are all sorts of aspects of law and society that the religious would class as being against the will of God but few of these issues create as much activism as Gay marriage. Surely there are all sorts of things that Muslims do that they disagree with but allow them to get on with. Praying to a different God for one, surely that really pisses him off. Why are they not willing to let non-Christian homosexuals do as they please as well?
As I have said and from a personal experience of many people against it, I think there is a large degree of homophobia underlying the campaigns. It is clear from the rhetoric of the argument that they see this as a great evil and a grave danger for society. They have completely failed to point out exactly how this will be the case. What is their vision of the future in 40 years time after gay marriage has been legal for that time? Few would say it aloud but I think they are worried about the spread of homosexuality and think that gay marriage signals further acceptance of gays in our society. I think there are some that see this as an 'enough is enough' situation.
They are free in our society to believe what they wish, but it is somewhat ridiculous in this day and age to think that they can affect how an atheist homosexual wishes to live his life in a diverse secular country. Never mind 'hate the sin not the sinner,' a majority of our country don't believe it is a sin anymore. Why should they have to appease the people that believe they are a sinner?