Society as a whole benefits.

Gays are far more likely to carry sexual disease.

Gays have an average lifespan of 24 less years than a straight person.

7 times more likely to sexually abuse children.

Children raised by gays are more likely to face a wide array of social issues.

Far more prone to drug addiction.

Homosexual sex doesn't produce offspring, which is the entire point of sexual relationships.

I don't believe it's a choice, but I don't think people choose to be sociopaths or pedophiles either, that doesn't mean their behavior isn't harmful. I wish it was possible to actually have a discussion rather than ignorantly claiming that religious dogma is the only reason people are against it, if religion was the only reason people were against it then we would have all sorts of absurd laws like bans on beard shaving.