This is why Christianity must be opposed instead of going "Those are not real Christians, everything is fine"
I mean I guess maybe I don't understand your vision on reform, then? Do you mean you have to change the name of something, not reform it? This isn't specific to Christianity by the way. Say liberalism, or conservatism, or whatever. I think it's
very valid to say "look, stop calling this <name of thing> because the things you're promoting are so far from the original movement that it's clearly not the same thing, even though you're using the same name."
On one hand the name of a thing isn't what matters anyway, it's the actions taken and their outcomes. On the other hand, you get easily persuaded people that say "oh we call ourselves members of group A, so we'll just blindly support anyone claiming to be from group A" - regardless of whatever it is that group is doing.
To say "we need to oppose Christianity" is also too broad - it's like saying we need to oppose cereal. What we need to oppose is "authoritarian Christianity", even so far as saying "look guys, this isn't even Christianity to begin with, because you are peddling something other than the Gospel." And yes, you can call people out on this - it's not subjective, and there are clear ways to determine what is and is not in alignment with the oldest copies of the texts we have. It's really not as mysterious as people would have you believe; in fact, it's the people that make it "mysterious" that are most likely to be in it for themselves.
People are too afraid to tell others they are out of line these days...