They do, at least in the recent evangelical world. In their minds these are the only things that will keep someone who believes out of heaven, and the worst kind of evil. A Christian can sin and commit horrible atrocities they say, because all is forgiven, except if it's being gay or trans, then they'll still go to hell.

This applies even to those who aren't hateful towards them, which until the last couple of years was the vast majority. In fact a person's opinion on these issues is usually considered THE litmus test for seeing if someone is really a true believer.

I don't see how they acquired this notion, and it's almost universally agreed upon. Jesus hated divorce and adultery, yet those things are only minor vices apparently, while something he never even mentioned is worse than the devil.