The trick is getting them to start questioning themselves and what they've been told. This is nigh impossible, since it's basically a cult. They're always told that they're smarter for listening to the cult, and that anyone who isn't part of the cult is a backwards idiot.

It basically requires that they have friends and/or family that haven't bought into the bullshit, and who they're also still willing to listen to. That's just the starting point and the questioning pretty much has to happen on its own after that.