Indeed, you are very right about some mainstream religion, but not about all mainstream religion.

Reform Judaism is pretty mainstream, and I can tell you from personal experience that acceptance is very very high in that world.

Likewise in most Episcopal churches, certainly in the World of the United Church of Christ, etc. Those are quite mainstream.

If those religious institutions can do it, then the world of evangelical Protestant Christians in the United States, and the Roman Catholic world certainly can catch up.

It's a question of good people standing up and demanding it.