Maybe not most, but most probably the majority. As far as I understood it, this isn't just some conspiracy theory, it's hard evidence.
Well, I'll guess more details will be revealed on the 19th.
If Christianity is truly nothing more than a fluke, than all of the sects that were rooted in Christianity are utter bullshit. But even then, this doesn't change the fact that people can believe in whatever they want. Just because Christianity is made up, doesn't make it any less legit than any other religion. Who's to say that any religion is legit? I hope that people will take this in a way that they now aren't forced to believe something, but that they can choose to stay Christian, because they want to believe in a merciful and kind god. But I think that Christianity needs heavy reforming from the ground up. If this actually happens, I hope that the result won't be just another religion with the purpose to control people, but something more.
Of course I am obviously having utopian dreams here and this will never happen because human nature is a tricky one.