More to the point, why do they believe the rest of us should be subject to their religious narrative alone?
There are a whole lot of science fanatics who believe that human beings are responsible for global warming. Whether or not what they believe is true, why on earth should they be permitted to create laws and place restraints on others who do not believe as they do? If we who believe in the God of Abraham were able to prove that God exists, and that there is indeed a narrative that God expects human beings to follow, would we then have the right to force our religious beliefs and narratives upon the rest of the unbelieving world and force them to comply?
I know, I know...you believe that people who pollute the earth and its atmosphere are causing harm to others, and for some reason, you believe that it is wrong to cause harm to others. And you then take these two beliefs that you have and use them to justify constraining others, and forcing them to comply with your own personal beliefs.
I personally believe that homosexual marriages and homosexual unions and homosexual relationships are a destructive force upon the society in which I have been raised. A society is the aggregate of people living together in a more or less ordered community. The society in which I desire to be a part of is, more or less, the society in which I have been raised. Homosexuality is in fact destructive to the society in which I desire to be a part of. Since a society is the people living together in community, harm caused to a society is a direct harm to the people who are a part of that community. Like you, I desire to prevent people from causing harm to others. I do not want my children hanging around with drunks and drug addicts because I do not want my child to become a drunk or a drug addict. I do not want my child hanging around with thieves, because I do not want my child to become a thief. These behaviors would be, in my opinion, destructive for my child, and I will do what I can to prevent my child from being harmed by the influences of these kinds of people. Put them in jail, let them die...whatever it takes to remove their evil influence over my child and the rest of the world. I believe in God, and I believe in the precepts that I believe that He has placed upon us.
Sin leads to death...not just death...death alone is no big deal. We all die...so what? I am referring to an eternal death of the soul. I know, I know...you don't believe in such things, but I do. Lots of people think it is wrong to harm others. But, not everyone that is a part of "our society" feels the same way. Some people have no sense of right and wrong. Some people take pleasure in causing pain and suffering to others. There are people that are a part of our society who do not believe in
all of the precepts that have been lain down by the society in which I was raised. But like you, I see no problem restraining people from doing things that I believe cause harm to others. There are five basic components of human societies: population, culture, material products, social organization, and social institutions. These components may either deter or promote social change. The common components across cultures are symbols, values and norms. But people within a society do not always share the same values. When the people within a society do not all agree on the basic precepts of that society, those precepts and therefore that society is subject to change, for better or for worse. Homosexuality is sin. That is what I believe. Those who sin are subject to a judgement of God that leads to eternal death. Eternal death, in my opinion is bad. It is something to be avoided. It is something that should be prevented whenever possible, what ever it takes. And so I also believe that those of us in this society who believe as I do, must do what we can to restrain other members of this society from causing harm, whether it be to others, or to themselves. By allowing people to marry other persons of the same sex, we are in essence saying that we don't really give a damn about homosexuals, and that we're really quite content letting them rot in hell.
I actually care to much about people in general to not want to subject them to my own personal religious beliefs.