Any discussion about sexuality is complicated by messy overlapping categories. Are there people who reject all homosexuality only out of religious faith? Certainly. Are some of them sexually uptight? Absolutely. However, it can equally be said that some atheists are perverts who, out of desperation or dogmatism, will have any sort of sex with anything, and have a knee-jerk sympathy for any sort of perversion.
The marriage debate is relatively unimportant except as a distraction from the central issue of whether gay people -and the rest of the alphabet soup -are suitable to be parents. It is simplistic to quote the bible because there have been huge technological changes, in hygiene with soap and indoor plumbing, in medicine with anaesthetics, surgery, and antibiotics, and high levels of prosperity and privacy that did not exist at the time the bible was written.
It's also simplistic to say that ALL gays are suitable to be parents. We don't know, and the social studies are unreliable: the social studies said that it was a good thing for Willie Horton to be released from jail, but Dukakis paid for that mistake when he ran for president. Oops: it's only the well being of children this time. We should have a program gradually expanding the right of parenting beyond the heterosexuals grandfathered in to progressively expanding categories of low risk gays.
We all know young handsome intelligent guys who could get any woman they want who happen to prefer men. We all know young beautiful intelligent women who could get any man they want but happen to prefer ladies. Many of these people are quite prosperous. These people would probably be suitable as parents. The best of these should be the first group enfranchised to raise children.
However, we all know there are a lot of scrawny pimple-faced boys having sex with each other, and a lot of old elephant hags having sex with each other. Many of these people are quite poor. What proportion of the gay population are they? If they are a majority, and we are doing an idiotically simple accross-the-board enfranchisement, higeldy-pigeldy at random by judges, then we are putting children at risk.
Atheists risk a backlash by their dogmatic and unconditional support for gay parenting if it fails in a high proportion. If large numbers of children adopted by gays get sexually molested, we will not seem very moderate, reasonable, or humane. It is an IF, but the arrogant complacency so reminiscent of the elitism of Lenin, is aggravating and dangerous.