Back in the early 1900s, women were discriminated against. We couldn't vote. We weren't encouraged to become educated, or to work for pay. Our role was defined by the husband, the children, and the home. If our husbands beat us, if our dates abused us, we kept silent, because that's what was done. All of this, simply because we were born female.
Back in the mid-1900s, black people were discriminated against. They were forced to go different schools than white people, to use different drinking fountains, to sit, most famously, at the back of the bus. The KKK sent its "message" of death with some regularity in its ongoing effort to show the blacks who was boss. They could marry each other, but they couldn't marry someone white. All of this, simply because they were born black.
Back in the mid-1980s, my uncle was still closeted because it was not in his best interest, economically or socially, to be openly gay. When he became ill with the AIDS virus, he was attacked on the sidewalk in his cushy Upper West Side neighborhood because the sores on his face, in his attackers' minds, confirmed his homosexuality -- therefore giving them free reign to beat the daylights out of him.
Hate crimes against gay people are still rampant; bullying of gay children has lead to beatings, murders and suicides. All of this, simply because they were born gay.
Those who base their prejudice on the Bible's teachings are cherry-picking their beliefs, which I would suggest invalidates them. Until we see, for example, Mitt Romney selling everything he owns and giving the money to the poor, which the Bible instructs, his use of the Bible to deny gay marriage will never be valid. Christians are also taught that God created us in His image ... and I doubt that He meant a white heterosexual male.
Those who suggest that gay marriage will destroy traditional marriage and "family values" are out of touch with the current culture. Our society is awash in single-parent households, multiple marriages/divorces, child abuse and spousal abuse. In fact, if I were gay, I'm not sure I would even want a "traditional marriage" as opposed to a civil union with the same legal/economic benefits. But that's me.
And those who suggest that gay people being allowed to marry will lead to people marrying their pets ... don't even warrant a response.
If Mr. Cathy of Chick-fil-A had suggested that he didn't believe in women in the work force, or that African-Americans deserved equal rights, he'd be taken to task. If Mr. Philips of Masterpiece Cake Shop chose not to make a wedding cake for a white woman marrying an African-American man, he would be taken to task.
So it's not about the chicken and the cake. It's about civil rights -- human rights -- and simply doing the right thing.