While I don’t deny that an uncomfortable proportion of people who are Christian are racist, sexist, homo/transphobic, xenophobic, etc, but to clump everyone into that category is straight up religion based discrimination.
I think you are frustrated by Christians who are bad people, not Christians in general. I know a lot of Christians, some who are terrible, and some who are genuinely good people. I also could say the same about the atheist people I know, the Jewish people I know or the Muslim people I know.
I think the problem is discrimination, which is common among (and contradictory to) Christianity.
I dunno about that. I think almost all of big box churches and even medium sized churches teach that. I would guess that over 90% of Christians believe that nonsense. But I would argue that they are not actually practicing the teachings of Jesus. Jesus loved everybody — sex workers, diseased people, etc. if Jesus were alive today I wholeheartedly believe he would be among trans folks and accepting them for who they are. Ultimately LGBTQ+ folks are fighting for the right to love which is also what Jesus fought for.
The Bible does not tell a story of Jesus rejecting homosexual people or transgender people, and in fact tells a story of someone who would love everyone, including the ones most Christians hate. Full stop.
Church + religion != Christianity.
For what it’s worth I am a staunch atheist.