is there a good argument that is non-theistic or non-religious to prove or at least argue that same sex marriage is immoral?
i cant think of any, and i dont want to use religious doctines, personally i am in favor of same-sex marriage but igot assigned in my debate class to oppose it.
the main arguments against same-sex marriage seem to be mostly religious. though there may be people who are against it because they see marriage as a heterosexual institution (because that's how they were brought up?), and they see gay people as 2nd class citizens (not a "real" man/woman, goes against nature, etc.).
That's about all I can think of. Honestly I don't understand people who are against same-sex marriage.
No, because same-sex marriage is in no way immoral, or wrong.
If I were you, I'd go to your teacher and say "listen. I'm not against same-sex marriage, and, as an atheist, I can promise you that there is no such thing as a rational or non-religious reason to oppose it. I would prefer to argue in favor, or just not debate."
I'm straight as an arrow, but if I were put in that situation, I would request to be switched to the other team or refuse to debate.
Actually, one time I got assigned to debating in favor of something I opposed (making marijuana legislation more restrictive [I favor legalizing it, myself]), and I sabotaged my team. We lost the debate because of me. Afterwards they complained to the teacher, but the other side (which was very much aware of what I was doing) stood up for me and said I did no such thing.
In your position, I would request a switch or refuse to debate. Your team cannot win. There is no legitimate argument against, but plenty for (the main one being that not only is there evidence of homosexuality throughout the animal kingdom, which means it is natural, but there's absolutely no reason, other than religious, to be against it) same-sex marriage.