I didn't say it did. What i meant is that my impression of choosing a vanishing event is so that the writer has the option to bring them up and that he's going to use it at some point.
I personally will be disappointed if the detail of vanishing people is only used to emphasize the piece's religious themes.
I don't know why you keep phrasing it that way.
Lindelof didn't choose to make them vanish, they vanished, it's a book, it was already decided, and the book didn't have anyone reappear so that is factually not the reason why it was specifically an instance of vanishing.
You could ask why he didn't choose to change the vanishing to something else, certainly he changed things, Garvey's actually the major in the book for example, but it's also clear from things like the titles and the heavier involvement of Wayne and the Priest, that he has absolutely no intention of diverting theories away from the Rapture.
I'm not saying it won't happen, maybe the last scene will be Nora and her family on a lovely summer's day in the park, but the decision to have them vanish was made by the author, not Lindelof, and it was made for a book without any explanation as to what happened, not a TV show that might one day explain it.