The real bone of contention is whether "sin" exists

I do not think that the queer community is intentionally asserting that there is no such thing as "sin", i.e. that there is no such thing as right versus wrong. But their attack on the viewpoint that queer sexuality is morally wrong, i.e. is a sin, has the effect of undermining the Christian teaching that sin exists. This is a comfort to all who feel guilt.

I am not a sinner when I shoplift. It is just my "orientation"; I am a kleptomaniac by nature. I am not a sinner when I beat my wife. It is just my "orientation"; I am a male trapped in a nonviolent society that gives me no other outlet for my natural violent inclinations. I am not a sinner when I expose my penis to young schoolchildren walking to school. I am just very lonely and have a psychological need to connect with other human beings, and when I expose myself I don't feel lonely. Etc. Etc.

The concept of sin plays a much larger role in Western moral philosophy (Judaism, Christianity, Islam) than it does in Eastern philosophy (Hinduism, Buddhism, Confucianism). Both philosophies use the carrot and the stick to promote morality. But Western philosophy uses, in addition, rebuke speech. Rebuke speech is unpleasant for the listener. Possibly the main reason that people in the West do not go to church on Sunday morning is that they don't want to be rebuked, to be told that they are sinners, to be told that the various pleasures that they indulge in, like stuffing KrispyKreme doughnuts into their 400 lb. bodies, is a sin. Such people find comfort in the current fight for legitimacy by the queer community. If queer sex is not a perversion but only an "orientation", then I am also absolved of my gluttony.

That, I think, is the psychology behind the broad support that the sexually normal people feel for the queer community's current legal initiative.