I’m well aware that some gay people are religious. The existence of gay Christians isn't counterevidence to my point.

I’m not saying that all religion is anti-gay. Rather, I’m saying that, if a certain opinion is anti-gay, it doesn’t matter whether it's uttered in a religious or non-religious context — the opinion is anti-gay per se. Religion isn’t a moral shield for it.

If I discriminate against you for some part of your identity (ethnicity, religious denomination, age, ability, whatever), it doesn't help you if I say that my religion told me to do it. Invoking religion as a shield might help me get away with bad behavior, but it doesn't help you deal with the fact that I'm discriminating against you and being antagonistic toward some part of your identity.

I would like everyone to recognize anti-gayness before someone literally throws a gay person off a roof. The bar needs to be lower than the rooftop.

I’m unconvinced that someone can “support” another community while voting against their rights. To follow through with your example and make it more precisely analogous: If a Christian believes it should be illegal to be Jewish, or even that Jewish synagogues should not enjoy the same legal recognition that Christian churches do, that Christian doesn’t really “love and have respect for Jews.” They're manifesting disrespect via their anti-Jewish position. It doesn't help the Jews if the Christian says their religion requires them to take this anti-Jewish political position. Pointing to some version of Christianity as the source of the anti-Jewish position may even make it worse for the Jews, as it implies that the anti-Jewish opposition isn't merely personal but is organized.