Yes same sex marriage bans are just as wrong as the past laws. There is no harm in people choosing to get married to people of the same sex. It is simply people living their lives the way they want to live them and not causing any harm to anyone.
It's two consenting adults who love each other who want to get married. Is it that much to ask for? Interracial marriage went through the same process that gay marriage is going through now. Each state, one by one, is legalizing it, and eventually, a court ruling struck down all bans. Gay marriage will have the same fate.
My opponent is taking a very narrow-minded view in what the purpose of a marriage in society is. According to my opponent, the sole purpose and primary requirement of a marriage is to birth a child together. This definition of marriage would exclude many heterosexuals who are infertile as well. In addition, we are not threatened by any sort of population shortage whatsoever. So this really should not be the issue at hand here. In a free society, consenting adults should be free to make their own choices and enter into whatever contracts they may choose, regardless of their race, gender, religion, etc., as long as they are not infringing upon the liberties of others. You have your own definition of what reflects a "natural relationship" or a "natural union," but this is not shared by everyone. Some have more expansive definitions, others have narrower definitions. Many people, especially in the days of anti-miscegenation laws, would not consider a white man and a black woman to be a natural relationship. Thus, a vague term with no universally agreed upon definition should not be used as the basis of our legal system.
My opponent is taking a very narrow-minded view of the purpose of marriage in society. My opponent argues that the sole purpose and primary requirement of marriage is to have a child together. My opponent's definition of "sexually healthy" means that only men and women who are fertile represent a "natural union" and a right to marry. This would exclude many heterosexuals from marriage as well. Regardless, we are not suffering from any threat of a population shortage so the argument is moot. The fact is, in a free society, consenting adults should be able to make whatever choices they want and enter into any sort of contract they want to, regardless of their race, gender, religion, etc., as long as they are not infringing on the liberties of anyone else. You have a perception of what makes something a "natural relationship" which is not shared by all, and others, especially years ago, would consider a white man and a black woman to be an "unnatural relationship," because their definition for that term varies from yours.
I'm a white guy. If I go out and find a black woman, no matter how black, if she's healthy sexually and so am I and we have sex we will eventually conceive. Even if we couldn't we could at least in principle. We reflect a natural relationship. People of the same sex cannot do this physically with each other no matter what. Not even in principle are they able to. They do not reflect a natural union. Animals don't count they generally don't maintain unions they way people do. Nor are they exclusively homosexual the way people are.
Gays should be allowed the right to be legally married. However in a religious marriage, I feel that it should be up to the individual church who would be doing the ceremony. I am a non-theist, but even I feel that a religious wedding is supposed to be between a man and a woman.
Banning interracial marriages and insisting on the traditional notion of marriage are two different things. Interracial marriages have been common throughout our history. The practice has been common. As a matter of fact, entire groups of people have been formed as a result of mixed marriages (a better term for interracial marriages). The ban on interracial marriages in America was down to keeping the races separate, considering that interracial marriages had been common.
Society has generally not considered the notion of same-sex marriage, not to talk of banning same-sex marriage; society's resistance same-sex marriage has stemmed more from rejecting the radically new idea on marriage for maintaining the traditional understanding of marriage.
Moreover, same-sex couples may marry even in states where same-sex has not been accepted without the threat of arrest, while interracial marriages on the other hand where criminally prosecuted (Loving v. Virginia).
The two are not comparable. Religious people and those in favor of traditional marriage are not the same as racists who stood against interracial marriages. It's apples and oranges.