Gay marriage is a matter of civil rights
Why do I support gay marriage even though I am not gay? Because it is a matter of civil rights. The majority of people who disagree with me use their voting power to elect politicians who continue to deny this basic civil right, just as politicians once denied basic human rights to slaves, who were deemed less than human by many people who should have known better, including Abraham Lincoln, whose best friend was a slave owner.
As I discussed in Meet the real Lincoln, Lincoln was a white supremacist obsessed with the idea of deporting all blacks; he spoke “in favor of having the superior position assigned to the white race” and claimed there was “a natural disgust in the minds of nearly all white people to the idea of indiscriminate amalgamation of the white and black races.” He regarded black people with arrogant contempt, viewing them as being somewhat subhuman and perpetually inferior.
Lincoln sometimes told “coon jokes” and referred to black people as “niggers.” Lincoln was the Commander-in-Chief of the Army when it hung some black men who protested how blacks were paid only half as much as the lowest paid white soldiers. Hanging black men who wanted equal pay for equal work puts Lincoln much closer to the KKK than to being the racial saint he is often depicted as being.
Slavery once was accepted by governments such as the United States and what I call not-so-Great Britain (for some very good reasons). Anyone who now speaks in favor of slavery would be viewed as a moral abomination. People will eventually realize that the might makes right principle that once justified slavery is just as misguided as discriminating against gay people whose minority status and hence lack of political power makes them easy targets for the majority happy to use their political power to deny a basic human right to gay people.
I've yet to hear an argument against gay marriage that isn't hogwash. Let's consider the most compelling one: that gay marriages might adversely affect children. Perhaps this misconception stems from an unfounded stereotype: that gay people are more likely to be child molesters. Wrong.
After my father decided he had better things to do than stick around and raise his children, his parental void was filled by a lesbian relative. Living with her for years didn't make me want women any less. Her imperfections were normal human flaws that had nothing to do with her sexuality; her reliability and parenting skills were a light-year ahead of my studly father, whose good looks and superficial charm made him a hit with the ladies.
Gay marriage is good for society because we all benefit from enhancing the foundations on which civilization is based. Marriage is a human construct created to foster relationship stability. Judging by how many heterosexual married couples act, even they have much to learn about relationship stability. Despite their imperfections, no one is suggesting that doing away with marriage will help them or help society; indeed, it would have the opposite effect. The beneficial effects of marriage will do no less to help gay people or help society, so permitting it is in the best interests of everyone.